electric vs gas water is simple. Everyone seems to claim that a gas water heater is the cheapest energy cost. But looking a little deeper I can’t find out how much energy will go up the exhaust flue. I mean evan if I find a direct vent water heater there is still a 4 inch hole letting warm air out 24/7 and cold air in.
I’m thinking that if our electric costs are faily modest and our gas prices are towards the expensive side the trade-off point might be that the electric water heater doesn’t need to be vented.
Seems like a worthwhile assumption but I simply can’t find the cost of a 4 inch hole. Any idea?
Replies
Frenchy,
We switched our house from oil heat and electric hot water to gas heat and hot water about 3 years ago. We kept the electric stove. I am in Maryland, just south of Washington DC. Our costs went down significantly. We went for an ultra high efficiency furnace, but a "regular" water heater. If it helps any, I just paid last months gas bill ... it was $18 That is for hot water only for three people. All three of us shower every day, probably 6-7 loads of wash each weekend. Dishwasher daily.
Frenchy
State has a few water heaters that use outside air for combustion. Kinda pricey though.
Mike
It's O.k. to think out of the box, Just don't walk off of the plank!
Edited 10/21/2002 10:25:49 PM ET by Mike S
Don't those yellow energy labels take that into effect? I've never stayed awake long enough to read through one of those things.
I test a fair number of gas furnace and water heater vents with a draft gauge; before they fire up there is relatively little movement of air through the flues (usually not a measurable amount.)
When they aren't firing, there is still usually some small amount of movement of air up and out from the warming of the flue itself; if there's cold air coming in, you have a high likelihood of backdrafting during operation (That's an opinion, I can't back it up with hard evidence.)
You can get flue dampers; I don't trust the bi-metal ones, they cause flue gas spillage at light off when the appliance is most likely to be producing higher levels of CO, and if they fail entirely most of the flue gases spill into the dwelling.
Electro-mechanical flue dampers are expensive, and I wonder if they are cost effective.
Edited 10/22/2002 12:54:15 AM ET by Bob Walker
I'm with Mike. The newer models with a fan are much more efficient, and some of them use outside air. I really like them.
I seriously doubt that the flue heat losses are included in the calcs on the yellow labels.
Spend the afternoon. You can't take it with you.
Frenchy (and Bob),
"Seems like a worthwhile assumption but I simply can't find the cost of a 4 inch hole. Any idea?"
The AFUE rating of appliances takes into account, to some degree, real world installation.
Unless the space the DWH is located is kept very warm, losses through a properly installed flue/vent are not that great. , For instance, a 4" pipe with gravity and/or a slight pressure (i.e. wind) driven flow will pass 30 cfm, at most. At -15 outside and 70 inside (degF) the energy loss would be about 2800 btu/hr. Reality would be a small fraction of that, unless you had no cap, exposed directly to the north wind. That would be a "bad" installation, to say the least.
Tim,
Thanx.
Slight thread drift: 60,000 btu 90+ furnace using house air for combustion and 40,000 btu side draft direct vent DHW in a confined space.
I've always used the 1 sq in/ 1,000 btu free vent space calc, but in the Bachrach Carbon Monoxide course I took a few months ago, they mentioned that the direct vent water heaters basically use th draft inducer to dilute the flue gases by some huge amount to be able to vent them through the walls,
If that's the case, how would one figure the air supply requirements (or "confined space" definition)?
What caused this concern is last fall I was on the roof installing an antenna and while the hot water heater wasn't firing, I could still warm my hands on the heat coming out. It was about 20 degrees and I felt a nice warm 70 degree draft coming out.
I'm now installing in floor radiant heat and I'm super insulating the house (11 1/4 inches of foam on the roof alone) The idea of cutting a hole thru that insulation to let heat out gives me the willies.
Thanks for your numbers I'll start to crunch them tonight
Bob,
First, the easy part. A confined space, per IMC Code definition is: "A space having a volume of less than 50 cubic feet per 1,000 btu/h of the aggregate input rating of all apliances installed in that space" An exclusion for direct vented appliances applies. Almost all mechanical rooms fall into this category. I would not change this based on induced draft appliances being used.
For transfer air from adjacent spaces, 1 square inch (free net area) per 1000 btuh is required. For outside air provided to a confined space, 1/4000 for direct openings and ducted vertical openings, 1/2000 for horizontal ducted openings.
The code does not directly address air used to dilute flue products as in an induced draft type. My experince with these type of vents (my DWH is this type) is that the "huge amount" is relatively small, and for the purposes of meeting the code and for safety, insignificant. In a truly "unusualy tight" construction, I would add 10% to required free net area, for good measure. I have no technical basis for this.
In the case you mentioned, 100 square inches of net free area, split between two separate openings, one near the floor and one near the ceiling, would meet the code requiremnts.
Tim
Back about 15-16 years ago, when we really had awareness of energy costs, conservation, and all that, there was a program on PBS called "Housewarming" They had a companion book to the series that may be available still. It was a very good series that had a lot of contractor, builder, and homeowner interaction and taught a great deal about heat loss, the quality of a tight envelope, insulation, and how to's. They did a lot on retrofitting as well as on how to build tighter on new construction.
I recall they actually did measure the volume of warm air that went through such things as the water heater flue. They even measured the volume of hot air that moved through a can fixture into an attic and from a bathroom fan into an attic. I dont recall the figures but it was enough to make me only use can lights in a first floor, never into a second floor, and I built my home with no exhaust fans in bathrooms.
To the original question, if the objective is to have the least negative impact on overall heat loss in the home, the answer is clearly electric. The other way to ask the question, given the choice in your home, would you have a 4 inch pipe open to the outdide, run from your heated basement, to and through your roof or just not have that pipe at all and keep the envelope sealed and intact?Wine is God's way of capturing the sun.
That is exactly my thought. But the anal me needs to put numbers together so I can make a judgement about currant and future costs.
I worked for several hours last night trying to understand the energy system well enough to make a judgement from that perspective.
For example there is an abundance of natural gas and the price is currently reasonable. According to what I read supply while decreasing should meet needs for the next 20 years. (which is really the effective life of any system)
On the other hand demand for electricity is increasing at a extreme pace and there haven't been too many additional sources brought on line while the pressure on existing sources is growing steadily. For example hydro electric has been villified because of the damage done to fish, and the increase in flooding plus the silt build up problem.
Nuclear is just about DOA and coal is causing acid rain.. the wind farms aren't profitable yet and solar isn't developed.
Yet in my rough calculations it seems to be the answer
You didn't mention that most new electric plants are now using natural gas. (I think)
How would that mess up your figures ???.............(-:I once had a cookbook entitled, "When It's Smoking, It's Cooking, When It's Burnt, It's Done".
Here's a chart (attached) on the a California study on nat gas from a few years back for your perusal.
"... and I built my home with no exhaust fans in bathrooms."
Energy conservation measures must not be allowed to force one into making bad decisions. No exhaust in bathrooms, besides being a code violation in most juridictions, is a bad idea. Exhaust and ventilation is essential to indoor air quality, and in many instances helps to protect the structure from trapped moisture.
"Back about 15-16 years ago, when we really had awareness of energy costs, conservation, and all that,..."
This, by the way, is about the time all the current mold "issues" really began, and when the "sick" buildings were created.
Tim we could debate that point endlessly no doubt. but I think to assume that the lack of a bathroom fan would rot the house is not a major issue for me and I dont think for most. Not one time was our home ever failed on code for any violation and in the three baths we have, we have no fans. From an energy viewpoint, they are a simple hole in the envelope and will always contribute to substantial heat loss like any such hole would.
One of the issues with building a tight home and making sure that all the major sources of heat loss and air infiltration are dealt with can be that the house gets too tight. When that occurs there are major problems with air quality and that led to more use of air to air echangers. For most people that is not a problem because to build a home that tight requires a lot of attention to detail that many builders either cannot or will not do. In the past 10 years, the focus on conservation and energy awareness has fallen back to the pre 1980 level for a whole host of reasons.
Refering back to "Housewarming" they had some excellent programs on super insulated homes built in Canada back then and as I recall, some in the dakoy=tas and Montana that were really fun to watch and see how the builders worked to tighten up the final product.
When Gas gets to 3 bucks a gallon and LP and NG double, the focus and attention will probably get back to those days.Wine is God's way of capturing the sun.
"Housewarming with Charlie Wing"....thats the book for that old PBS show if interestedWine is God's way of capturing the sun.
My assumtion was to use air to air heat exchangers when I reach the point where my envelope is fully sealed.
I planned on exhausting the bathroom air (as well as other air from around the house) into them and extracting the heat prior to exchanging it for warmed outside air.
I notice they aren't sold at the big box stores so I assume that either they aren't catching on or they are somehow flawed.
In fact I don't remember seeing their installation in any of the thousand or so homes I've visited this past year that were under construction.
The fact a big box doesn't carry something means that they can't get volume....trust me air to air exchangers are not rare, they just need a pro, not a dIY projectWine is God's way of capturing the sun.
Please don't take this the wrong way, I'm asking it as a question rather than a challenge.
Why do air to air exchangers need a pro? Aren't they just a buch of ductwork and a fan?
OK sizing would require some study, but I've figured out everything from wiring/ plumbing/ furnace ducts/ and infloor radiant heat so far on this project.
Besides it's not like brain surgary where if you're a fraction off the guy dies.
So far everything that I've seen has been do rough calculations based on certian formula's and assumptions and then look to see what fits closest.
Now I understand that I may not be the smartest guy on the planet and it's possible there are some things I'm completely overlooking, but what else would a pro do besides what was just mentioned?
Frenchy,
" Aren't they just a buch of ductwork and a fan?" Heat recovery ventilators (those that transfer only sensible energy from air stream to air stream) consist of two fans in a box, a heat exchanger, and usually a filter or two and some simple controls. An Energy recovery ventilator, which transfers sensible and latent (i.e. humidity) energy are more complicated but the main diference is in the "exchanger".
Installation of the device is not beyond a DIY, if they could replace, say a gas water heater.
" So far everything that I've seen has been do rough calculations based on certian formula's and assumptions and then look to see what fits closest.
Now I understand that I may not be the smartest guy on the planet and it's possible there are some things I'm completely overlooking, but what else would a pro do besides what was just mentioned?"
A professional HVAC engineer/designer would size it to meet the code ventilation requirements for the space, taking into account the occupancy, the capacity of the equipment used to condition the space, the sensible to total heat load ratio, and check everything out on a psychrometic chart to see if you could get to the design conditions on the worst design case day. That's for the supply side.
I can't say I remeber the details of your intended use, but sizing the device for a single family home is a simple matter. It just depends on what you want it to do.
If you are interested in using it as a means to provide good quality air throughout your house for general purposes, I would recommend that you size it to bring in and exhaust the flow rate equivalent to 1 to 1.5 air changes per hour(ACH). That calculation is straight forward. The total floor area of conditioned space x ceiling height / 60 will give you the cfm required to mee the air flow you need.
If you want to just use it for bathroom exhaust, size it for 10 ACH for the bathrooms only.
If you have some other use in mind, whatever it is, it can be accomodated.
Tim
Tim,
thanks that is great! exactly the reason I am so active on this board.
Air exchangers are very rare here in Minnesota. I visit approximately 1500 new home sites a year in Minnesota and I have seen less than 10 installed or about to be installed air exchangers.
That's 10 over the past 10 years! I would think that they are very needed here but they are so rare that I began to question the wisdom of my choice.
The information you provided me will give me a basis to start seaching for a source of them for the DIYer
Frenchy,
Don't let the common poor practices disuade you. The wisom, on your part, is there, uncommon though it may be. I know the expense of these devices is not insignificant. Not providing fresh air to homes, especially homes that are better sealed and insulated than ever before, is a poor practice.
If you need resources to locate heat or energy recovery ventilators, let me know. In MN, you will probably want one, if the price is not too high, that will transfer heat and moisture. Winter outside air, as I'm sure you're well aware, can be very dry, and summer OA can be 90% rh at times. Managing the humidity in your house is an important consideration, as well as fresh air.
What part of MN?
Do you have a particular make or model in mind?
Tim
Thanks Tim,
I need a consumers report on them, you know? Heck I don't know enough to evaluate 'em and the "pro" is just gonna sell me what he installs. any suggestions? If the cost and quality of most are similar then I'll use the standard fall back position, second grade math.... That's cheaper than that!
Frenchy,
I can provide you with some information on the ones with which I am familiar.
Considering the range of manufacturers out there, and I'm sure like SUVs-alot are jumping on the bandwagon, it is not a simple evaluation. Cost will eliminate all but HRVs and ERVs (see below).
To make sure that we're on the same page, terminology-wise, these are the types:
Heat Recovery Ventilator (HRV)-an air-to-air heat exchanger (HX) that transfers heat energy only, no humidity is tranfered. This type typically has a waffled or corrugated metal exchanger, air in does not mix at all with air out. These are very effective in winter, but will add humidity to the space in the summer.
Energy Recovery Ventilator (ERV)-an air-to-air cartridge-type of heat excchanger that transfers heat (sensible) energy and humidity (latent energy). They have a propriety "cartidge" or core that transer heat and some moisture. In some cases, these are better than HRVs. The summertime effectiveness of these is poor compared to the following, but the price makes them much more realistic in many applications. This is the type that I will be installing in my house.
Energy Recovery Unit (ERU)-this type has a rotating wheel, made of plastic or aluminum, coated with a desicant or a proprietary "molecular sieve". It transfers heat and latent energy very effectively, but they are very expensive. The various technologies, and benefits of each, is beyond this discussion.
Suggestions: determine the air flow rate you need/want; determine the conditions that you want to evaluate the units for (-15 outside to 70 inside winter, 95 outside 75 inside summer, plus humidity if applicable), get some prices with performaces and compare.
Here is an article from JLC on installing HRV's.
http://www.jlconline.com/cgi-bin/jlconline.storefront/3dbe997600023f8f271a401e1d290608/Product/View/0201inst
" I planned on exhausting the bathroom air (as well as other air from around the house) into them and extracting the heat prior to exchanging it for warmed outside air."
This is a very good idea. One that is beyond most contractors. If you have nultiple bathrooms and you want the exhaust to be intermittent, control of the unit will be more "interesting".
In large buildings, I regulary use the ERU/ERV and the exhaust fan and fresh air supply. As long as exhausts are not chemical in nature, the small amount of cross contamination in wheel-type ERU's is insignificant.
"I notice they aren't sold at the big box stores so I assume that either they aren't catching on or they are somehow flawed."
The cheapest units on the market are still fairly expensive. The smallest, least effect unit that I know of, the Renewaire EV-130, cost $860, last March. In a size large enough to be of any real benefit (say, the Renewaire EV-450), the cost was $1920, last March (the latest pricing data I have).
You won't find any solar collection or wind generating equipment at the "box" stores either. Not a good indicator of flawed technology.
"In fact I don't remember seeing their installation in any of the thousand or so homes I've visited this past year that were under construction."
Also, not a good indicator of any thing but cheapness. I'll bet there was plenty of vinyl siding on those homes, right? You probably didn't see a single home with: make-up air provided for combustion or exhaust (not need at Cheifs house), or fresh air ducted to any furnace.
Tim
How often do you see anything in a new home that means more up-front cost, with the return coming over time? HRV's are not cheap to purchase (which puzzles me a bit), and the savings (there WILL be savings) might not come back for 5 years, depending on your climate. You also have to factor in the increased indoor air quality with an HRV, which is rough to put a $$$ value on. Kinda makes me think about how many peole (me too) wake up stiff because they won't spring (ggg) for a new mattress, despite the benefits of a better quality of sleep.
Your anaolgy of a mattress is a good one, I recently bought a very expensive mattress because it felt very nice on the showroom floor and was told in depth how great it was.
the problem is compared to my old one I wake up stiff and sore and wish I'd selected another brand/type.
Which is exactly my feelings about HRV's.. They just aren't common enough yet for there to have been a natural selection process. this is a good reliable one that is priced fairly. (the way there is for furnaces and water heaters etc.)
You might have a look at http://www.lifebreath.com . Pretty good stuff. Can't tell you what the price is, though.
To build a house with no bathroom fans would suggest that no one in the house will ever take a shower or a long hot bath, or else that you keep your windows open all the time. To have such a major source of humidity and warmth together with no ventilation is not just an invitation to mold, it is a demand for it. here in eastern canada, you would never get away with it, and let me tell you, we worry about energy consumption. you would have a hard time selling that house around here, too.
Good point.
"... to assume that the lack of a bathroom fan would rot the house..."
That is not the assumption that I made. How old is your house? How much have seen inside the walls? If you are not venting bathrooms, especially those with tubs and/showers, be certain, you are causing water/moisture damage to your house. It may not "rot" but you are growing mold in your walls.
"Not one time was our home ever failed on code for any violation and in the three baths we have, we have no fans."
There are poorly trained individuals in the inspection side of the building trade, as well as the construction side. Because you have managed to get away with a poor practice, does not change the fact that it is a poor practice.
"From an energy viewpoint, they are a simple hole in the envelope
and will always contribute to substantial heat loss like any such hole would."
I disagree. What do you mean by a "substantial" heat loss?
Am I to believe, then, that your house has no plumbing vents, a dryer vent, kitchen exhaust, water heater or a furnace/boiler vent?
"When Gas gets to 3 bucks a gallon and LP and NG double, the focus and attention will probably get back to those days."
I agree with this completely. Many old and new mistakes will be made.
"One of the issues with building a tight home and making sure that all the major sources of heat loss and air infiltration are dealt with can be that the house gets too tight."
I disagree with this. A house or a building cannot be too tight. A building of "unusually tight" construction, is less forgiving if improperly vented/exhausted/conditioned. Competent design can accomodate a tighter construction than is reasonable to build.
"When that occurs there are major problems with air quality and that led to more use of air to air exchangers."
Unfortunately, this is not true. The situation has led to need for more heat and/or energy recovery ventilators, but not their use.
Excellent discussion but I have to respond and respectfully disagree. On the bathroom ventilation issue, you are clearly overkilling with vents. In 16 years, none of our bathrooms have any signs of any mold or impact from moisture. In all cases the rooms are wallpapered on at least two walls with no probles that would indicate moisture issues, not has the paint or varnish shown any. To make this point the clearest, consider how long a mirror has moisture on it after a bathroom door is opened...its gone in minutes. As well, any bathroom should have a heat/cooling duct run to it that will forceably push new fresh dry air in very quickly. Again, I think your issues with this point are moot.
Id challange your code understanding. No where can I find any code requirements on forced ventilation in a bathroom.
"From an energy viewpoint, they are a simple hole in the envelope and will always contribute to substantial heat loss like any such hole would."
I disagree. What do you mean by a "substantial" heat loss?
Again consider this in its simplest form...given an alternative of no 4 inch hole or a 4 inch chimney from basement to roof, you have to agree that no hole is going to allow far less air than a 4 inch stack. I did not imply or say that I have zero holes in the insulation envelope, but if it were possible, that would be the desired end result. To your point, is any heat loss a good thing if it can be avaoided?
"One of the issues with building a tight home and making sure that all the major sources of heat loss and air infiltration are dealt with can be that the house gets too tight."
I disagree with this. A house or a building cannot be too tight. A building of "unusually tight" construction, is less forgiving if improperly vented/exhausted/conditioned. Competent design can accomodate a tighter construction than is reasonable to build.
"When that occurs there are major problems with air quality and that led to more use of air to air exchangers."
Unfortunately, this is not true. The situation has led to need for more heat and/or energy recovery ventilators, but not their use
In these two statements you have shown a bit of lack of understanding or just have not had the experiences that bear out these statements. In fact homes can be built tight enough that air quality is a major issue. The use of mechanical means like air to air exchangers is a direct result of tight homes. The issue of too tight is debateable as many times the design and attention to detail is desired and the exchanger is part of the building plan and design. But to say a home cannot be too tight with todays systems of insulation, home wraps, caulk/sealants, high tech windows and doors is simply not true.
I dont understand your last point...are you saying that air to air exchangers have not been used?
The debate rages on!Wine is God's way of capturing the sun.
"Id challange your code understanding. No where can I find any code requirements on forced ventilation in a bathroom."
I'll accept that challenge because I can find many. One example: the International Mechanical Code (pick a year) requires, in toilet rooms and bathrooms for private dwellings, single and multiple, "Mechanical exhaust capacity of 50 cfm intermittant or 20 cfm continuous".
Most Building Codes: IBC, RBC, BOCA, CABO and UBC, will allow "natural ventilation" in lieu of mechanical, provided "openable window area meets a minimum percentage of the floor space.
Though I do not have them all memorized, you pick the code, I'll point out the requirement.
" To your point, is any heat loss a good thing if it can be avoided?"
Avoidable heat losses are a waste. Nobody will disagree. My point is that some heat losses cannot be avoided. Ventilation is required, and with the exchange of conditioned air with fresh air comes at a cost. Costs of ventilation can be minimized, with good design, but not eliminated. Accomodating all needs of occupants in any building is a compromise. The cost of ventilation vs energy conservation is one such compromise.
"In these two statements you have shown a bit of lack of understanding or just have not had the experiences that bear out these statements. In fact homes can be built tight enough that air quality is a major issue."
There is a lack of understanding here. The "issue" ONLY arises when a builder or architect or owner builds a "tight" structure and fails to incorporate proper ventilation. Therein is the lack of understanding. If you build a very tight structure but do not treat ventilation requirements PROPERLY, you create a poor environment.
"The use of mechanical means like air to air exchangers is a direct result of tight homes."
This only partially true. In the post energy crisis world, outside air (ventilation) rates were reduced in an incomplete/incompetent attempt to reduce energy consumption. Without the necessary ventilation, equipment designs were modified to accomodate only the absolute minimum and were "value engineered" to be more cost effective. As indoor air quality, mold, personnel productivity, sick buildings, etc., issues arose as a direct result of improper ventilation and inadequate equipment designs, the response was to increase ventilation rates. With higher ventilation rates than the equipment is designed handle, energy and heat recovery ventilators became about the only means for competent designers to utilize commonly available equipment and produce an acceptable indoor environment. As a result of common use in commercial and institutioan use, smaller versions came available and are starting to be used, on a limited basis in residential application. The fact is, 95% of new residential construction has "contractor designed" HVAC systems, and are entirely inadequate to meet the demands of tighter construction.
"The issue of too tight is debateable as many times the design and attention to detail is desired and the exchanger is part of the building plan and design. But to say a home cannot be too tight with todays systems of insulation, home wraps, caulk/sealants, high tech windows and doors is simply not true."
Again, my point is, if the only component of the design that is addressed is the building shell, then you are correct. I consider that poor and incomplete design. The key word in your statement is "simply". In tight construction, simple is inadequate. It is unfortunately, very prevalent. You cannot build a structure that is so tight that it cannot be properly ventilated and have excellent indoor air quality.
"I dont understand your last point...are you saying that air to air exchangers have not been used?"
I design HVAC systems, and where required, regulary specify and include in my designs, energy recovery ventilators. Architects, owners and contractors regularly cut these from the budget. My point is that they are used MUCH LESS than they are required.
<snip>
Tim we could debate that point endlessly no doubt. but I think to assume that the lack of a bathroom fan would rot the house is not a major issue for me and I dont think for most. Not one time was our home ever failed on code for any violation and in the three baths we have, we have no fans. From an energy viewpoint, they are a simple hole in the envelope and will always contribute to substantial heat loss like any such hole would.
<snip>
I hate to disagree, but I must. Not having an exhast fan in a bathroom is a bad idea. Where I live code 'requires' one. This above statement puts much more faith in codes and inspectors then I have. Not every good thing is in the code. Not everything in the code is good or even makes sense. Even the best inspector may have simply assumed there were fans and never noticed their exclusion.
But as far as the fans 'always' being a hole in the building envelope...Not Necessarily. When I install a bathroom or kitchen vent fan I:
A) Put it on a timer so it can't accidentally be left on.
B) Install a roof vent w/ a damper in it so it's only open when the fan is on.
C) Build a sealed box in the attic over the fan housing to stop air infiltration.
D) Seal all ducting connections tightly.
E) & If someone's hyper concerned w/ it, I wrap fiberglass insulation around the vent ducting in the attic.
After all of this, air leakage is near zero. An air exchanger would be a great addition. My 30 yr. old house, despite my best efforts works well just w/ leakage.
Oh, doesn't appear he's ever been in my bathroom right after my daughter finishes a shower. Even w/ the fan on everything's dripping.
Of course, she likes a hot shower, and if you forget she's in there she'll shower until the water gets cold. & I have a 75 gallon water heater.
As I rember even with the high energy costs back then the pay back on most of the fixes was 10 years or more.
Some information that might be of interest regarding this thread is the "R-2000" program in Canada. You should be able to find it with a try on your search engine. A lot of builders (in Canada) still adhere to the principles that came out of all this research and development. It changed the way builders do things, and the average consumer (client) around here is quite aware of the R 2000 program also. We use this info as we teach our fourth year Carpenter apprentices about energy effiecient construction techniques.
On a different note, I am just having our latest home roughed in for plumbing and heating and we have only one bthroom fan for 2 1/2 bathrooms. But we are having an HRV (Heat Recovery Ventilater) installed and two of the intakes are going to be in the other bathrooms. This more that meets code and the requirements of the R-2000 principles for controlled air exchange for a tight building envelope.
Jeff Up North
4" holes are free. They ship them loose with every direct vent HW heater.
Trust that this one it isn't even close to even for electric.
what you're looking for is a water heater with a damper.
if the damper fails to open during ignition, the unit willl shut down, not throw CO into its surroundings. but then, water heaters should be located in garages whenever possible. aside from CO, when many water heaters are not maintained, they have a nasty habit of going because the tank gets holes and now you have a flood...
brian
Brian,
I'm sorry, water heaters in our garages would not work.
It gets to 30 below in the winter here (sometimes colder) . A lot of garages aren't heated, or attached to the house.
In addition with a pilot light and gas fumes from a spilled can for the lawn mower, etc. the potential for disaster is too great. I've got friends in Calif. who have not only a water heater but clothes washer and dryer too! It may work there, not here....
Frenchy,
When you buy a water heater, you should check out the Energy Factor (EF) for the unit. The EF is a measure of the efficiency of the unit in a simulated use condition. It takes into account all factors relating to energy used and lost...flue losses, energy to run fans, etc. Most electric water heaters has EF's between .90 and .95 while gas heaters have EF's between .58 and .65. The diffence is largely due to two factors. First, the conversion of gas energy to hot water via a flame is not nearly as efficient as an electrical heating element. Secondly, heat is lost up the flue during standby.
While it is difficult to easily improve the first factor, heat loss thru the flue can be lessened by fans, dampers, etc. Hence, these more expensive units will have higher EF values. As a water heater company employee, if I were building a new house, I would buy a power direct vent unit with the highest EF available. That will maximize the efficiency while still allowing the use of the cheaper fuel...natural gas.
I hope this helps!
Bill