Replies

1. 
   IronHelix | Dec 31, 2003 03:40pm | #1

   Dennis...............take a look at the metal spec tag on the boiler.  It should list the maximum imput BTU's/hr, which will allow you to calculate how much propane will flow into the boiler when the valve is opened for firing. It should also give you a maximum output in BTU's which will allow you to calculate the basic unit efficiency.

   Max Output divided by the Max Imput tomes 100 = % boiler burning efficiency.

   So your calc at 1.12 gal consummed per hour of burn are correct.  Boilers are "on" or "off", there is no in-between for the consumtion rate.

   BUT,the efficiency of the boiler and heat loss calculations for the house will determine how often and long the boiler will need to fire to keep the desired temp.

   So 10 gal/day is about 930,000 BTU =38,750 BTU/hour of heat loss or .41 gal/hr.

   Ask your propane supplier to give you the degree days for the last month, then ask the boiler salesman to help you do a heat loss calc for your home. 

   Is the boiler too small to keep up?....who sized the unit?

   How are you trackiing the time the boiler is burning?

   Is the boiler burning correctly?

   Is there a damper control on your boiler?

   Is your RFH slab insulated from the perimeter of the exterior wall? 

   Is your construction not yet tight enough to keep the heat inside?

   Is the water heater side of the boiler functioning properly? 

   Do you cook with gas?  Is there a gas clothes dryer or other gas appliance?

   Sorry for more questions than answers!

   ..................Iron Helix

1. 
   DennisS | Dec 31, 2003 07:37pm | #4

   Thanks for the reply I-H;

   No other appliances currently connected to the system - will have a propane cooktop in the kitchen when the cabinets are done. Electric oven and clothes dryer.

   I'll contact the propane supplier to get the degree days info - good thinking! thanks

   Boiler operation time is recorded on the control module for the boiler. Records total operation time since initiation of service. I built a spread sheet where I record the date, time, hours of operation, tank gauge reading and so forth, then calculate the gallons used per theoretical consumption based on boiler run time and actual gallons used per tank gauge reading. The tank gauge is pretty small and not graduated very well so it's a crap shoot to decipher gallonage to any degree of accuracy. None the less, I'm seeing about a 50-60% effeciency based on the data that I'm able to record.

   It seems fairly obvious when looking at the house that heat loss is the culprit. What surprised me, as I mentioned in the orignal post is that the month of Oct. was the coldest weather we've had with the exception of the past week or less yet the fuel consumption during that time was far less than for the period from initiation of service (June) to the first part of November.

   The heating contractor sized the boiler and system. His co. is established and experienced in the area so I have to assume he knows what his business. The (gas piping) system held 20lbs air pressure for several months between the rough-in and the actual hook-up to the tank and turning on of gas.

   I'm considering installing a meter in line to better monitor the fuel flow. Are you familiar with any kind of metering device that's not too costly to purchase and install? The propane supplier told me such a unit would cost around $200 - something similar to a natural gas meter. Seems there should be something less obtrusive and less expensive.

   Oh - your other questions -

   The concrete slab fill is separated from the wall by 3 1/2" so for the present there's minimal perimeter heat loss.

   I'll have to check on the flue damper but I'm pretty sure there is one.

   I suspect the house just simply is too 'open' right now but ..... sure don't understand the October heating costs being so much lower than what followed.

   ...........

   Dennis in Bellevue WA

   [email protected]

1. 
   GARY2568 | Dec 31, 2003 08:23pm | #5

   Hi Dennis,

   I know where you are at, I was there 4 years ago when we installed a full radiant system in our house. I was looking for lower heat bills and was real surprised to see the boiler go thru propane (expensive propane) the same as you are experiencing. Frustrating, in light of the claims that RFH is supposed to be so economical. Just for some comparison, presently, I heat 3300 sq. ft above grade for around $100 per month during our coldest months (-5 to 20 degree days).

   I found out a few things. The first was that the in-direct water heater was malfunctioning, our water temps on the readout were supposed to be 125, I was measuring 120-155. Finally a service guy found the sensor probe had fell out of its holder. Put that in, it held the water to within 3 degrees of the set point. That went on for the first 6 months (winter, early spring). Used lots of propane, 300 gallons a month in real cold winter months. So I figured most of my heat was in cycing water heater, summer came and I watched my propane drop in the tank quickly still, turns out I used close to $300 of propane to heat water for 5 summer months. My old house used $15 per month of NG for the same period. I talked to my installer, he said that maybe $60 per month seems high for the summer, but in the winter, I'm probably getting the hot water for nearly free so it evened out.. My confidence in my heating guy took a dive, I started learning all about this system and finally ripped out the in-direct water heater, put in a 75 gallon stand alone unit, and now I'm back to $15 per month for hot water. I think that was alot of my problem.

   The second was the propane itself. I had NG out at the street, but it would have cost $6000 to run the underground back to my house, so my installer ("you can by alot of propane for that, how about fuel oil???!!!") told me to go propane. NG is a whole lot more economical burning than propane, so after the second winter ($800 heat cost), I had the gas company bury a quarter mile of line (that was almost the funniest day of my life, but another story) and now I use NG both in my house and barn workshop. I don't have exact numbers or BTU's, but my costs for the coldest months (Jan-Feb)don't get over $125, and are usually around $60-100 for the other 4 months.

   The third thing I learned was about boiler efficiency. Mine is a Slantfin 150K BTU, 80% eff. But that is the best eff. it can achieve running at optimal conditions, it's probably closer to 60% in normal running. One reason is the size, mine is sized to handle the indirect water heater which is now gone. So I have a too big boiler. The other reason is in the mixing. I have a Tekmar control that measures outside temp, inside temp, does a few calculations and delivers the water temp to the floors based on that. I can set the heating curve number that has a lot of bearing on that water temp setting. If the setting is to low, water temp is low and the boiler has to cycle alot. Lot's of cycles, low efficiency. So I talked to a boiler friend, he said to put some mass to that thing. I will put a 30 gallon reserve tank next to the boiler one of these days, I expect to gain a better efficiency when I do that also. These new boilers just don't have much mass to them, they cycle alot, and the efficiency drops. Wished I had known that before, I would have looked at a more efficent combo heater that would heat domestic water and then run a loop thru that to heat the floors. Currently, my mixing valve is constantly opening and closing, a combo heater or injection system would even that out and the water temps would be more consistent too.

   Sorry for being so long here, I probably could have added a bunch more, but these few things are the main problems I learned and fixed. (I also had a loop hooked up backwards!) I'm not convinced that in-direct water heating is the way to go. I also think you have to look not only at run time, but also cycle time in a given time period. That might be most of your problem right there.

   Good luck, it's frustrating, but talk to lots of people, you'll get a handle on it.

   Gary VanDeWeert

   Richland, MI

   30 degrees and bright sunshine today

1. 
   DennisS | Jan 01, 2004 06:06am | #8

   Gary -

   Thanks for your extended commentary about your experiences. No apologies required - your information is appreciated!

   Yes, if NG had been available where I am, I would have opted for that as well. We heated and produced HW with NG in our old house and I'm sold. I didn't even consider oil since we were planning on gas for cooking as well and thought it would be a 'natural' (no pun intended) to go with propane for single fuel use for everything except the clothes dryer.

   I'll definitely bring some of the issues to light with my heating contractor!! I plan on spending another week or so monitoring the system to see what results.

   The most bizarr thing seems to be going on, though.

   Currently we here in the Puget Sound area are experiencing a spate of cold weather. (cold is relative I realize but .... it's *cold* for us!! haha). Judging from the readings from the tank, we've used next to nothing with respect to fuel. Atleast compared to the last month. Granted I've turned the heat way down (we're not living in the house, BTW - while it's under construction) and I've gone through and plugged up lots of holes and installed insulation in places that needed it.

   I'm still getting used to this new, new to me system. But based on your experiences, I think I need to have a heart-to-heart talk with my heating guy ..... again! (grin)

   Thanks very much for your input, Gary. Lots of good information has been coming to the fore!

   ...........

   Dennis in Bellevue WA

   [email protected]

1. 
   migraine | Jan 01, 2004 07:13am | #10

   What you are going through is exactly my concerns for putting a RFH system in the house we are building now.  So far, most responses are that they love the system, but I have not really gotten much feedback on the actual operating costs.

   I will be looking forward to the feedback you receive from others concerning your situation.

   We just had our first snow while living in Ocean Shores.  Sorta strange to see snow on the beach, at least for this California transplant

2. 
   DavidThomas | Jan 01, 2004 01:08pm | #11

   When bulding my house, the most the heating system (50,000 BTU/hour input) would do is 20F above ambient. Working in 40F is brisk but a lot better than 20F. Until the urethane foam was sprayed in place, there was massive air leakage. Which I knew.

   So it was a little strange to sealing up every little plumbing and electrical penetration when I knew I had tens of sq ft of holes in the envelope.

   Once the foam was sprayed, all was good. Tested 5 times tighter than any house the inspector had done before. NG consumption was 0.07 BTU/hr/sq ft/F. So x 1700 sq ft and x 110F (70 - -40F), I use 13,000 BTU/hour when it's -40F outside. I'd designed around 0.1 but hoped to do better. And did. Space heating and DHW off a single HWH.

   Design an air-tight envelope. Watch the details during construction. Until the envelope is tight, of course you'll suck fuel.David Thomas   Overlooking Cook Inlet in Kenai, Alaska

3. 
   MarkH | Jan 01, 2004 05:20pm | #14

   Granted I've turned the heat way down (we're not living in the house, BTW - while it's under construction)

   Are you sure your propane isn't being pilfered by the local neer do wells? It happens.

4. 
   KARLSTER | Jan 01, 2004 07:07pm | #15

   Martha,

   Interesting idea.  Are you suggesting someone has tapped into his low pressure (after the regulator) gas line and is piping it to their home?

   Or are you suggesting they are using his tank to refill portable propane tanks?  If so how would they do it? 

   The only way I have ever succeeded in transfering propane from one tank to another is by turning the supply tank upside down to ensure that the Liquid propane flows into the empty tank.  If I keep it right side up all I would get is a small amount of propane vapor. 

    To further speculate on this scenario they would have to disconnect his high pressure line and later reconnect it which would cause his pilot lights to go out and his gas lines to acquire air which would need to be purged before an elec ignitor could light it.

   The only other possibility is if some regions it is standard practice to add a valve to the bottom of the tank to tap into the liquified propane for refilling or to supply fuel to an internal combustion engine.  A thief could use such a valve as an eay means of refilling portable tanks but I have yet to see one installed except on propane fueled vehicles.

   I get the feeling I am missing something.  Can you provide a bit more detail on the scenario you visualize?

   Karl

5. 
   MarkH | Jan 01, 2004 07:17pm | #16

   I can't offer any suggestions to how this is accomplished, but one thing I have learned is that anything can be stolen.

   Here's something interesting: http://yarchive.net/car/rv/propane_refill.html

   Edited 1/1/2004 11:21:02 AM ET by Martha Stewart

6. 
   KARLSTER | Jan 01, 2004 07:19pm | #17

   The only way I know of to steal propane realistically is to hoist the tank onto a flatbed truck and drive away with the whole thing.  Obviously this is not the case in this thread.

   Karl

7. 
   MarkH | Jan 01, 2004 07:23pm | #18

   See my previous post. I didn't know of this either. (http://yarchive.net/car/rv/propane_refill.html)

   Edited 1/1/2004 11:43:53 AM ET by Martha Stewart

2. 
   greggo | Jan 01, 2004 08:12pm | #19

   Hey Gary :just curios to what type and make indirect w/h you had? And what make and type you have for the new one.

    My house is 3100 sq ft and my heat loss only came out to about 102,000.I have a Buderus oil fired  boiler (120,00 doe capacity,ibr 104,00 net) and Buderus 79 gal w/h which have not been run yet( walls not up)

   When I called Buderus ,they told me that I did,nt need to calculate the w/h for the boiler sizing,it would go into the priority mode for hot water.They were more concerned about sizing the w/h to my 100 gal whirlpool.All of the reading I've done ( and its only reading  mind you LOL) suggest that the indirects are the one of the best ways to go for hot water because of the minimal standby loss (for mine its suppose to be about 1/4 o  an hour). and heat loss going up the flue. Just curious and wondering at the same time.

   Thanks for any input

   Greg

1. 
   GARY2568 | Jan 03, 2004 05:25pm | #20

   Hey Greg,

   My in-direct water heater was a 40 gallon Amtrol, capable of 200K BTU/hr. The dealer's claim was that I couldn't use hot water fast enough to run out with this unit. He was probably right, but not for the reason he claimed. The tank came with a 3/4" cold in and hot out. But the top tank fitting was a proprietory brass tee with a special thread to the tank so the fitting had to be used. A T&P valve screwed into the top, hot water supply came off the side of the tee. The tee fit onto the tank thru a fitting that had only a 5/8" hole in it, once the probe for the T&P went into that hole (1/4" probe), the net hole size dropped to 3/8". It is a bit defeating to put 3/4" pipe in the house with a 3/8" supply hole on the heater. So I raised the T&P out of the fitting about 2" to still give heat sensing, but allow me to have a bigger supply. The inspector was OK with my plan, he said he would have done the same thing. I guess my biggest fault was the fact that I had a 150K burner (boiler) on this water heater all summer, and it cycled alot. That, IMHO, is a big heat waste and contributed to my huge gas bills during the summer. Coupled with the fact that the water heater sensed very precisly, and would cycle for a 2 degree heat rise if called for.

   I now have a 75 gallon AO Smith stand alone with 75K recovery set at 130 degrees, with a Sparco mixing valve to balance hot water to 120. Last T-day, we had 4 showers running together for 45 minutes to get everybody to church on time, never ran out. My heat costs are in line with what I expected to pay.

   In my situation, I think this in-direct unit was an energy waster, and I'm quick to suggest to anyone that putting one of these in is NOT a good idea unless the dealer will back up his claims with hard facts. I know of 2 people who didn't listen to me (my brother is one), he is taking his out in March.

   Gary

2. 
   greggo | Jan 04, 2004 09:00am | #21

   High Gary Thanks for the reply. It definitely sounds like your boiler was over sized,that would cause the sort cycling,what was the heating contractor thinking on that one.

   I had several guys come out for my estimate on the heat loss caculation.No one was even close to each other .I realize that no one would be exact with the numbers but 72,00 102,000 and 134,000 and that was working off blueprints with new construction. Some dealers will just do a rule of thumb by the Sq.Ft.then add x amount over to cover there a*s.The unit then gets sized to big ,hence the short cycling

   I haven't heard a good thing about the amtrol indirects,especially with well water(coils tend to get a lot of gook on them)

   Check this book out if you can/Consumers guide to home energy savings 7th edition(I think they make an 8th)by Wilson ,Thorne,and Morrill) I paid like $7.50 at amazon used,lots of great tips (boilers ,w/h windows etc) 

   I also have two slantfin boilers in the house that I live in now ( personally I think that they are middle of the road) as far as quality.I switched to a Buderus for my new house.

    Stay Safe Greg

   Edited 1/4/2004 1:05:32 AM ET by GREGGO10/2 10/3

3. 
   Lateapex911 | Jan 05, 2004 12:29pm | #24

   I'm heating my shop with propane, and when I installed it, the propane folks warned me that as the outside temps go lower, I would get less BTUs out of the gas, as my tank is located outside. My experience is that it does seem to be the case.

   But nobody here has mentioned that factor, so now I'm begining to think I might be imagining things.   Is this an actual factor, or is it a non issue??Jake Gulick

   [email protected]

   CarriageHouse Design

   Black Rock, CT

4. 
   IronHelix | Jan 05, 2004 02:20pm | #25

   But the gas is burned inside the house....so it still has its rated BTU's. It even has the same BTU's if burned outside the house.

   What the gas people refer to is the loss of vapor pressure from LP as the temperature drops....somewhere around 40 below it just about quits vaporizing.

   As the temps go below zero the rate of evaporation from liquid to vapor is reduced and the vapor volume/pressure available for piping to the boiler/furnace is diminished.

   The other contributing factor is evaporative cooling as the liquid LP boils off to form the combustible vapors.   Roofers using 100# cyliinders to fire off a tar pot have a high rate of consumption as compared to the surface area of the liquid. As the liquid LP boils it cools the tanks and LP to the point of frosting the exterior and significantly slowing the burn of the tar pot burners. In the cold season this requires tanks to be set aside to warm in order to be used adequately and finally emptied.

   Put a 100K BTU Torpedo Heater on a 20# LP Cylinder and watch what happens at even 20 degrees.

   That is why a 500 or 1000 gal tank is essential in a cold climate to allow for adequate surface area for evaporation to gas for high consumption rates without extreme cooling that would lower line pressures to the appliance to the point of burner inefficiency or even malfunction.

   Frosting of the tank and loss of vapor pressure is seen locally (Southern Illinois) when heavy winter use loads are placed on cylinders up to 250 gallon.

   ......................Iron Helix

5. 
   Lateapex911 | Jan 06, 2004 04:28am | #26

   Thanks for that very infomative description! I have a much better understanding now.

   I think that I have seen the beginings of a loss of vaporization situation, in cold ( approx 10F) temperatures. Is there any way to protect, or to insulate the tank? Certainly bringing it indoors would work, but we can't do that, now can we!? What, other than a much larger tank, might help push the onset of the problem to colder temps?

   Thanks!Jake Gulick

   [email protected]

   CarriageHouse Design

   Black Rock, CT

6. 
   IronHelix | Jan 06, 2004 02:59pm | #27

   What size tank do you have?  Is it on the sunny side of the building?

   The vapor pressure (V/P) of propane is 110 PSI at 70 degrees, but at 10 degrees is only 31 PSI....and at -10 the VP is only 17PSI...so you can see that adequate vaporization rates in cold weather are often critical to an efficience burn in cold weather.

   There is a formula for calculating VP tank capacity.  You need to know the tank dimensions, the current temp, and the % of fill.

   Diameter of Tank x Length of Tank X "K" (Constant for Each % of fill) x "M" Air temp Multiplier = VP capacity in BTU/Hr.  Send me your numbers for a calculation. What is the heater consumption rate?

   Some areas bury the tanks.....but it requires a specially built and painted tank plus a sacrificial anode bag attached to prevent electrolysis.

   Tank size does effect the VP rate as per the formula. And percent of fill factor K is 45 at 10 % fill and 100 at over 60% fill.  M is 1.00 at O temp, but is 2.00 at 20degrees.

   .................Iron Helix

7. 
   DennisS | Jan 06, 2004 06:57pm | #29

   X911 -

   Not sure about that.

   The lower the temps (around here the last week we've had sub freezing weather) the slower my tank gauge goes down but .... the boiler run time remains about constant. Not sure how this correlates with respect to fuel useage and outside temps.

   I've got a 500 gallon tank located outside (of course) and in the late summer monthes with high humidity, I noticed frost on the outside of the tank when the boiler was running for any length of time.

   ne uses only what is vaporized in the tank. If the cold weather causes slower vaporization, I would think you'd simply use less, or perhaps the same amount, just take longer to burn it ..... or something.

   Obviously I don't have a clue on that one.

   ...........

   From Beautiful Skagit Co. Wa.

   Dennis

2. 
   blackcloud | Jan 05, 2004 07:58am | #23

   Dennis,

   I saw the same results on my fuel use (oil) as you are for your system.  The only thing that I came up with is the sun was further north in Oct. and had a lot more of it.  By the way I am across the sound in Seabeck.  Hope this helps.

   JasonIf it wasn't for bad luck I wouldn't have Any!

1. 
   DennisS | Jan 06, 2004 06:48pm | #28

   BC -

   Shorter nights, longer days ..... I hadn'g taken that thought into account! That definitely *would* make a difference.

   Thanks

   ...........

   From Beautiful Skagit Co. Wa.

   Dennis

2. 
   Poolman | Dec 31, 2003 06:12pm | #2

   Simple place to start; a propane boiler will use aprox 1 gal. of fuel per 100,000 BTU (bolier fuel consumption is determined by input BTU) for each hour of run time.  You boiler will consume just over 1 gal per hour regardless of its efficency.  "Efficency" measures how much heat is theoretically applied to your heating needs vs. "wasted" (up the chimney, etc...)

   Assume all lines were properly pressure trested prior to being placed into service; leak testing at boiler gas valve once gas turned on?

   untill the circumstances change, my answer will remain the same...
3. 
   Poolman | Dec 31, 2003 06:17pm | #3

   Re-read origional post, looks like leak has been ruled out, sorry!

   Another note, propane tanks only have about 50% of their rated volume as usable fuel.  A full tank should not be much more than 80% full and is generally considered "empty" between 20-30%.  This is to allow vaporization of the liquified gas into the gas state that is actually used.

   untill the circumstances change, my answer will remain the same...
4. 
   booch | Dec 31, 2003 11:20pm | #6

   I read thru the posts and I didn't see two of the biggest culprits of lost heat.

   1. is the whole chimney thing. That includes the damper on the boiler exhaust, Fireplace use, and any other appliances or vents that blow or vent outside the house. Big air there. The fireplace you may be using to supplement your heat could be, at minimum, sending a couple of air changes per hour out the stack. Using a damper and a glass door over a traditional fireplace opening will save you lots of energy. Plug it, damper it, or find out where the heat is going out.

   2. infiltration is the second issue. It would be a cheap experiment to walk around the house with a box of kitchen matches and light them one at a time and hold the flame near faceplates, windowframes, entry doors, attic entries, and foundation joints. From that point a case of greatstuff will patch most of the benign joints. (obviously not the outlets)

   Your equipment room (boiler room) does it have an external air inlet to feed the burner? If not you are sucking hot air from the house to feed the chimney.(consequently creating drafts) No matter what the literature says about the "features" of a new boiler / furnace, quality systems use exterior air to burn and forced ventilation for the exhaust. Ohterwise you'll never be truely efficient as a system.

   Especially look at your entry doors. Got any kids? (they leave the doors open like it is the middle of July) Simple storm doors caulked at the frames and tight fitted exterior doors will warm up your building.

   Windows of course have an R value of 1 to 4 in my half baked conversion to R-values. If you have single pane windows this might be the culprit.  Storm windows, that plastic sheet stuff, or most other hardware store bandaid will show benefits.

   As a recap of your and others comments. The sillplate & the attic are your biggest heat dissapators. Insulate them as much as you can afford. Dividends on insulation pay for the materials in our climate often within 3 years of heating expense saved.

   If there is a big wind in your area consider plantings to put your house in the lee of the winterstorms.

   Winter is not for sissies.

   Start with the matches. That ought to be the biggest learning experience you'll ever have.

   Jack of all trades and master of none - you got a problem with that?
1. 
   DennisS | Jan 01, 2004 06:18am | #9

   Booch -

   Thanks for your input.

   The boiler is located in the garage which is attached to the house but no communicating doors. The garage doors are open all the time - in the construction state, ya know! -haha-

   I made a cover for the fireplace until such time as we can afford a nice glass reasonably tight glass door for it. Boiler flue is, of course, in the garage with the boiler so there's no flue loss of inside air from it, either. Do have a semi-air tight wood cook stove (small Jotul) in the kitchen that we use sparingly.

   No kids .... well, they're grown and on their own and paying their *own* heating bills now! (grin) But did add weather stripping to all the doors today. Most needed it!

   Windows are Pella wood casement with self storing storm sash. I call them storm sash since they're not really as efficient as true thermal (dual paned) glazing I know. But at least they're not single pane. All are in quite good operating condition considering the age of the house (almost 30 years old). All close tight and lock with the locking levers.

   The next level of sluethdom will be to investigate the second floor ceiling/attic interface to see what I can do there to stem the flow of heat laden air molecules. The last owners had an electric forced air furnace in this place - downdraft - with half the ductwork in the crawl space practically falling apart. How *they* ever heated the house is beyond me. Although the neighbors' comments lead me to believe they were outdoors-ish types and probably weren't bothered with such creature comforts as space heating!

   Based on what I'm seeing of the fuel consumption with just the cursory bandaids I've been putting here and there, your assesment about the infiltration would appear to be spot on. Over time I intend to do a more detailed job of separating my inside self from the elements.

   Thanks very much for your comments and suggestions.

   ...........

   Dennis in Bellevue WA

   [email protected]

5. 
   greggo | Jan 01, 2004 04:16am | #7

   Hi Dennis:the book I got shows the Buderus #G124X25 gas fired cast iron boiler @ 103,000 BTU input  DOE capacity BTUH @85,000  A.F.U.E% @84.2

   That was for NG not sure what the conversion to propane would be,but someone here will chime in

   Hope this helps

   Greg

6. 
   IronHelix | Jan 01, 2004 04:06pm | #12

   With the boiler in the garage....all the heat from that boiler mass goes to heat up mother nature and not the house....maybe adding a "boiler room" with vents to the house envelope would put some of that heat where it belongs!

   My boiler is located in a basement  utility room that is 14x34....the boiler keeps that room quite toasty.  We converted parts of our house to RFH and RBH in 1997 and have found it to more comfortable and affordable than the electric baseboard in the bedrooms and the forced air furnace in the living area.  No regrets!

   There was enough price difference in our then propane costs and an available supply of NG that we piped in 3300 feet of poly gas line to the house and boiler! Payback hs been accomplished this year.

   In regard to the metering of the propane....lots of money....and the boiler recorder added to the gallonage on the delivery tickets from the propane company will allow you to calculate your rate of consumtion close enough. 

   Tank gauges are notoriously inaccurate....when we were on propane there was a large stone kept under the 1000 gal tank cap for rapping on the tank gauge to cause it to adjust to be read.

   From other posts it seems your state of construction allows for your heat loss...tighten up the house and you'll tighten that wallet.

   ..............Iron Helix

7. 
   DanH | Jan 01, 2004 05:17pm | #13

   Another thing to keep in mind is that, with in-floor heating, it takes a while to heat the ground beneath the floor. Once it's heated the ground becomes a "thermal mass" that moderates the temperature of the floor.

   Also, keep in mind that there can easily be a 2x difference between a house that is under construction and one that is all buttoned up tightly. Paying careful attention to eliminating air infiltration can make a big difference.

8. 
   davidmeiland | Jan 04, 2004 11:58am | #22

   Great puzzle, Dennis. I'll throw a couple of probably-irrelevant things out there since I can't think of anything likely. The logical thing is a propane leak, but I assume your propane supplier did the low-volume-leak test after everything was connected.

   Is there any possibility of a slow leak from one of your heating circuits? If there is, the cold water being fed into the system through the makeup line will force the boiler to heat colder water than the usual return water in the system. If there's a leak you can't see (yet), this may be part of it. You've stated that the boiler is running about the same amount. If it's a modulating-type boiler, it might run hotter with colder water coming in and do the heating it needs to do in roughly the same time as it would with warmer water and a smaller flame. Don't know the Buderus at all, but I did shoot a nail into a piece of tubing once and it was not evident for several days and then only one and a half floors down. Took a long time to trace and the system ran well during that time.

   And, any possibility of one of your mixing valves somehow keeping the water to the boiler too cold? Water would be escaping the system if that were the case, and could do so either from a leak or from one of the pressure relief valves. I assume you have checked the pressure relief outlet, wherever they are (should be outside).

   It is not my experience that radiant is cheaper to run, it's just way more comfortable. Last house we had ran a small boiler and tubing under the floor (100K BTUH 80% boiler heating 1300 SF). We loved it dearly. Folks with similar sized homes and scorched air systems reported similar heating bills. I never measured but I'm sure the boiler ran more than 3 hours a day during high demand, and your house is probably bigger than ours was. Now we're in Friday Harbor and subsisting on a couple of electric heaters while we remodel. It's about 14 degrees outside at the moment and I'm pretty sure the line from our well is frozen underground.