Radiant heating using staple up method
A couple years back I had the great idea of having my heating contractor install a radiant system for me. It has never worked as I expected and now after researching a bit and the fact that it seems to have improved greatly in the last couple years I believe I know why but would like some more professional opinions before spending more money. The main floor with the radiant is only 20′ x 26′ and has four loops of roughly the same length. The tubing is 1/2″ PEX using a plastic clip that holds the tubing about 3/8″ away from the bottom of the subfloor (3/4″ Ply). Under that is about a 2″ airspace and then 9″ of fiberglass insulation. This is all above a finished basement that is kept at about 55 degrees during the winter. I have a Buderus G115 boiler which circulates the water to the Wirsbo header. I have a separate baseboard zone for both the second floor and the basement all with independent circulators. I have a finish floor above the radiant of standard carpet with rebond pad. I know now that is a recipe for disaster which it is.
Now to the fixes to improve this mess. I plan to rip up the carpet and pad and install an engineered 3/8″ hardwood floating floor on the surface for starters. Then underneath I believe I should rip down the insulation and replace the plastic staples with aluminum heat transfer plates along the entire length of the PEX. I forgot to mention before that I have two runs of PEX in each truss bay which are 16″ o.c.
I have also read that I should install a foil reflector with a 1-2″ airspace between the tubing and the fiberglass insulation to keep the heat going in the right direction. I was thinking of using 1/2″ foil faced insulation board as it seems like impossible to keep foil in place with all the obstructions I have to work with plus the fiberglass.
I believe I will also need some other controls (floor thermostat or computer for the boiler?) to control the water temp for the hardwood floor as they what a max temp of 85 degrees.
I know I will probably need some professional help with the controls, but I want to do what I can to cut the labor costs as much as possible.
Any suggestions will be greatly appreciated!
Replies
Can you afford to lose any ceiling height in the radiant area?
If you are going to the extent of ripping up floor and ceiling, you may want to consider abandoning the existing system and start again on top with the new low mass pre-formed systems, which have the aluminum plates built in.
This is Wirsbo Quik Trak
http://www.wirsbo.com/images/showroom_quiktrak1_1.jpg
RBean
web: http://www.healthyheating.com
blog: http://wonderfulwombs.typepad.com
First things first? I'm sure I'll contradict what others will offer, but that's what RFH is all about.
Without any calculations in hand and without knowing where you live, my first thing would be that since you plan on doing it anyway, to rip down the basement ceiling.
Then remove the FG batts.
Then pick up a RFH staple gun and use the plastic staples to staple the tubing directly to the underside of your subfloor. I'd forgo the Al plates for now.
I'd then do just what you suggested...add 1/2" foil-faced polyiso rigid foam board insulation (RFBI). Rip the 4' by8' sheets to a width ever-so-slightly wider than the gap between your joists. You'll get the hang of it after the first few rips. Then friction-fit the polyiso between the joists, up against the bottoms of the staples. The staples will naturally hold the RFBI about 1-1/2" away from the subfloor.
Then put all that delicious FG insulation back up in the bays, tucked up against the bottom side of the RFBI.
If you can get that done this fall you can live with the system over the winter and see if the system shows improved performance.
If you really want to get rid of the carpet (not just because of the RFH) then that would be my second move.
You probably already have a mixing valve to take the 160-degree water off the boiler and make it a RFH-friendly 110-120 degrees, that should keep the wood floors that will replace the carpet happy. Are you nailing it off? If so, and your higher motivation is to ditch the carpet for wood flooring, then I'd drop the loops before nailing the wood down. Not a big deal since you;re going to eventually staple them up.
If you;re considering a glue-down engineered flooring, then you can do the staple-up first then the flooring. Or vice-versa. The choice is yours.
If you don't have an outdoor rest, that might be something to look in to getting. Essentialy, it's a thermocouple that goes on the outside of your house and sends a signal to the RFH system as to the outside temperature trend. Thus instead of the RFH system waiting for the inside temp of the house to drop enough to fire off the interior thermostat, the outdoor reset lets the system know that it's geting cold out NOW and that gives the system a bit of time to lead turn the requirment for heat. Essentially, it allows for a kinder and gentler RFH.
My last choice would be to actually install the Al plates. Although they might be helpful if you're in an extreme climate.
most of your problems stem from the people installing RFH that don't know crap about it but figure oh it can't be to hard! WRONG!!!!!!!!!!! more than half of the info thats posted here on RFH is wrong. Anyone that hasn't actually insalled it and is using it is guessing. Simpler is better by far. I have sat by reading for a year or more seeing all the bad info being dished out. Enough!!! Making it right won't be easy but pull down the ceiling and remove the batts. purchase al. plates w/double tube bends or get flat and make a small jig and use a 1/2 copper to bend in dimple twice, then staple that up directly to the subfloor, plate should be about 10-12" long then skip a space the same if under hardwood ,continous if under carpet. Use foil (you can get it in large sheets from supply houses) just cut it w/razor knife,staple to the sides of the bay. reinstall the insulation. Next ! you need to check the return temp from the loop to the boiler MAXXXXXXXX 10-15 Diff. from what it goes in at. While we are on that subject. Change the mixing valve up to around 130-138 closer to 38 most will tell you 110 or so your responce is terrible. People want an increase in room temp the same day they adjust the thermostat. keeping it at that temp will allow you to be able to setback at nite to around 50-55 at 10pm and call for heat at 4-430 am use electronic thmostats ,set differencial to 1 deg. standard honeywell is4-5 way to far to drop room temp. Some of the WIRSBO set ups use little zone valves,junk.. Each zone should have it's own circ. prefably a 3 speed one so you can speed up or slow down. Try most of that and see where you end up.
I totally agree floorheater, I helped my hvac guy do my staple-up, on my last house under carpet/ tile/ and hardwood. The only diff. was we ran the heat at 160, and the reflective material I used was a 15"x 30' roll of bubble rap W/ foil on one side I found it at HD, then the layer of R19 FG.
I could be wrong, but raise your temp before you tear out the basement ceiling. the foil is helpful but not completely critical. Setting your thermostat to kick on around 4:30am was key to making the house feel really warm for us.
the foil is most definatly critical. if you have the option pull down some of your fg batts and remove some of the foil put back the fg batt and check the temp under those batts definatly will be higher. I will not install w/o it, if customer wants to cut costs by me not using it ,I refuse the job no question.
I wouldn't go W/O foil either, my point is, is it worth taking down a finished surface.
A complete radiant system isn't eff. with out it , so yes I would. About 6 years ago we did the tests for BTU performance ,contoled enviroment the works, took us a week to complete. Tube only no foil , tube w/al. transfer plate no foil, tube w/foil, tube w/foil & transfer plate. You would not believe the diff. We aslo did the same w/different size tube.
part 1 of 2
I share the passion though I still say if cfordg can afford the height, I'm with COremodeler - leave the ceiling alone…you’re talking about ripping down drywall, pulling down batts of fiberglass insulation, refastening pipes, installing plates (Radiant Engineering – preferred brand) re-foiling and insulating then re-drywalling, mudding sanding, more mudding more sanding then one more mudding and sanding then a primer. If the ceiling is finished with a texture then add that into the project as well. It’s messy and labor intensive no matter how you do it - and it takes a skilled boarder and plasterman to make the ceiling look as good as it did (presuming it was a good job to begin with).
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The cleanest way - providing cfordg has the height to spare - is to pull out the flooring, lay down the panels…QuickTrak, WarmBoard…whatever ones favorite flavor - they all work…snap in the pipe and connect to the header…you can nail hardwood directly on top of these surfaces…no drywall, no mud, no painting, no disturbing the fiberglass…notta…you need your skill saw, a chop saw and a screw gun…that’s it...its simple – its clean - its fast and it works…and you don’t have haul out a bunch of debris from the basement.<!----><!---->
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Plus running up the temperature and adding more circulators although one of several solutions, is not quite in line with the whole purpose of owing and operating a low temperature system which is supposed to be efficient and comfortable. More temperature + more pumps = less efficient & less comfort. If one has to resort to these solutions it says there was no design, or it’s a poor design and/or a poor installation and/or something has changes since the original system. In some cases, the service technician has no choice and I have resorted to these measure myself…but in this case the customer is willing and able to make the corrections…now how’s that for a rarity? I say go with the flow...pun intended.<!----><!---->
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Also, the closer the fluid design temperature to the room temperature the better the stability of the control system…low temperature is better than high temperature…besides the fluid temperature - as we know - is not an arbitrary value. It is based on heat loss, floor R-value, and tube spacing. Pipe is the least cost item on the bill of materials…given a choice between running higher temperatures or using more pipe…in my books = install more pipe. The closer the spacing = the lower the fluid temperature = the more even the surface temperature = the more comfortable the client for the lowest possible energy bill. Since cfordg is willing to go the distance to correct the problems then what a great chance to start from scratch…ie: heat loss through to head loss calculation.
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As far as setting back the temperatures on a radiant floor…I’ve been doing this for over 20 years and have systems in both artic regions…all my houses but one have had radiant as have my shops and offices…setting back radiant in my experience ( I can’t speak for others) is like setting back the temperature on a swimming pool…may be for some – but not in my books unless its for long periods of time …but if one did believe in such things then a low mass – low temperature system is a friend.
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Incidently, we’re on our last phase of a complete overhaul on a property we purchased a few years back…have it all…radiant floors, walls and ceiling…the best system is a toss up between staple up with plates or the floor tracking systems with fluid controlled by weather compensation (aka indoor/outdoor controller or as outdoor reset as per Mongo)…constant flow – variable temperature. It is the best combination I have used to date.
As far as foil goes…it works. As far foil over the long haul…I’ve been on retro jobs where the foil was as pretty and shiny as the day it was installed but I’ve also been on one job where the dust was so thick on the foil it had the reflectivity of dirt. After the first three years the customer had to adjust his fluid temperature upward ever so often…we thought it was him aging! Lesson learned - eat crow when you are young and stupid it tastes a lot better than when you’re old and smart.
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RBean
web: http://www.healthyheating.com
blog: http://wonderfulwombs.typepad.com
Edited 9/14/2005 11:07 pm ET by RBean
Edited 9/14/2005 11:40 pm ET by RBean
part 2 of 2
When conduction is used - as in direct contact with plates or embedded in the floor assembly - one builds in long term performance without risking the chance of reflective degradation over time…it may not happen…but for me having been there - why risk the chance? In cfordg case if ceiling height is at a premium, then staple up with plates is the next best thing (my not so humble opinion)…as far as foil – install it if one likes…but don’t count on it being clean and shiny in ten years. A radiant wall or ceiling could be considered as well...also a lot cleaner to install than a ceiling retrofit.
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As far as delta t’s goes…here’s a link to a chart I created for our designers a decade or so ago. http://wonderfulwombs.typepad.com/technical_data/ The suggestion of 10 to 15 deg F is good providing that the resulting flow (which is based on delta t) is sufficient to keep the velocity in a good range. Small zones with small loads benefit from narrower delta t’s i.e.: less than 10 deg F. more so than larger zones as it relates to system 'hydraulics'.
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The comment on zone valves is interesting since radiant suppliers use private labeled products. None of the PEX producers cast or machine their own valves…the exception might be <!----><!---->Watts<!----> who own PEX extruders in <!---->Europe<!----> as well as valve production. In the case of several of the major PEX guys - the early version of valves were made by Erie, Flair, Honeywell, White Rogers or even some Tour and Andersson stuff, then Sparco came along ( which was purchased by Honeywell ), Braukmann (also owned by Honeywell), Taco, Danfoss, and of most recent years Molenhoff, Heimeier (once distributed by Taco but now part of the IMI Group which now owns the Tour and Anderson -Bal. Valve div.) and Oventrop. (Its all one big happy familiy) So any comment on zone valves is a poke in the pond. As far as reliability goes - a Danfoss RA -2000 series valve with either their own actuator or a Molenhoff actuator is bullet proof.
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The other thing I agree with and so eloquently stated by floorheater, “most of your problems stem from the people installing RFH that don't know crap about it but figure oh it can't be to hard! WRONG!!!!!!!!!!!” .......is well – pretty much bang on.
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What I can’t figure out is why people who buy cars, vacations and home appliances will do weeks and months of research and yet when it comes to spending an equivalent dollar for a heating system that they have to live with for 80% of the time and pay to keep it running 100% of the time - is brushed off as a Popular Science project….to me that is just – in floorheaters words - WRONG!!!!!!!!!!!
Please, no offense to the posters...pro's or DIY'rs...just pretend that the RFH system is a car..and do your homework. It is not - never is - as easy as it seems or as made out to be by some.
...forgive the long post but my skill in the short and sweet is in proportion to the holes that need filling...some just can do it in ten words or less! Sorry...will keep working on it...<!----> <!---->
RBean
web: http://www.healthyheating.com
blog: http://wonderfulwombs.typepad.com
Edited 9/15/2005 12:43 am ET by RBean
Edited 9/15/2005 12:50 am ET by RBean
Just so happens I'm on the cusp of a small staple up project, which is a 16X20 guest bed/bath adjoining a garage/shop. Joist space is accessable via a sealed and insulated crawl space. I've pulled the PEX and am ready to staple up light weight plates. So now have an opportunity to place foil or not.
(I did my house with DIY plated top-of-subfloor sandwich, and zone valves and the system worked really well over one heating season so far with nearly constant circulation in the highest loss zones, modulating boiler, occasional manual outdoor reset, with supply temps from 95*F in shoulder season and thaw weather, to 120*F during the coldest days and nights. Nearly constant return delta of 7*F. So I did put in the research and it paid off)
Back to the current project...I had planned to use FG batts tight against the plated PEX subfloor and not bother with foil, but floorheater's research on foil etc and your statements about foil are giving me pause.
About 6 years ago we did the tests for BTU performance ,contoled enviroment the works, took us a week to complete. Tube only no foil , tube w/al. transfer plate no foil, tube w/foil, tube w/foil & transfer plate. You would not believe the diff. We aslo did the same w/different size tube.
In the projects where you noticed that the foil remained bright after "years" versus the ones where it was covered with dust: Where did the dust come from? Was there a detectable difference in the construction/floor type/maintenance/ etc that you could attribute to the dust/no dust?
I my case, the conditions with a sealed and insulated crawl space and plywood subfloor finished with engineered hardwood finished floor would seem to rule out any entry of dust, so maybe the addition of a layer of foil bubble wrap or similar above the FG would be worth the small bit of expense, time, and labor.
floorheater will probably say, "just do it", and if he has time, I would really like more detail on his research, and I think it would benefit the radiant floor community in general as well.
Edited 9/15/2005 9:24 am ET by johnnyd
Edited 9/15/2005 9:27 am ET by johnnyd
Here's a link to what I would say has to be close to a perfect plate installation...superb workmanship c/o Glenn Kaufmann from Montana.http://wonderfulwombs.typepad.com/photos/tresure_chest/attachment.html
A note on low cost heat transfer plates or the wrong combination of PEX and plate. Any designer/installer long in the tooth has experienced the infamous 'ticking' sounds amplified with plate systems. Do not mess around with this - it will literally drive one and a customer nuts. Use only the plates provided by the manufacturer...and stick to high quality combinations. If one insists on mucking around by using brand, x pipe with brand y plates – all I can say is – good luck. I've been caught in the middle between two manufacturers before and it ain't fun.
The picture 3 below is a thermography photo showing four of several methods of installation. This came from the Kansas State University research project on floor assemblies c/o Bob Rohr.
Here's a link to an article covering the research on plates and air spaces…make note of the difference with air gaps also note the outputs over 30 Btu/hr/sf are not recommended outputs - one would never design to these values.http://www.healthyheating.com/downloads/Plate.pdf
As far as the dust we could only attribute it to the state of the sub floor, the project conditions during construction (wet and muddy) and the location - house sat in the middle of farm field - no trees - no hills - just the wind, dirt, gophers and grasshoppers.
If floorheater says to just do it...I would agree - there is no harm - it will perform just fine - from my experience (again I can’t speak for others) I just wouldn't count on the long term integrity of the reflectivity. It is definitely a grey area (pun intended) that needs to be looked into in detail.
I also want to point out that it illustrates how well systems perform when you do the homework and do the math...you're example with the constant flow - variable temp....7 deg F delta T is - well - worthy of celebration. Good job.
Cheers...
RBean
This link is to a picture courtesy of a gent who was also looking for help...besides the very poor design and installation...note the dust build up on the tubes ...which means its also on the foil....also shown is an install of the sub floor assembly systems. http://wonderfulwombs.typepad.com/technical_data/
web: http://www.healthyheating.com
blog: http://wonderfulwombs.typepad.com
Edited 9/15/2005 10:53 am ET by RBean
Edited 9/15/2005 11:09 am ET by RBean
Edited 9/15/2005 11:10 am ET by RBean
Edited 9/15/2005 11:33 am ET by RBean
Edited 9/15/2005 1:36 pm ET by RBean
This may not sound dramatic, but keep in mind that radiant heating with limited output and a simplistic tube pattern works a great deal better (more comfortable at the same temperature) with all the insulation you can get in the house's shell. A uniform tube pattern leaves cold areas along exterior walls and windows. People often under estimate how much air circulates between these cold spots and warm areas of the room.
Now if I could just think of something dramatic to say....hmmm.....
Dramatic thought #1: In a really well insulated 1000 sqft habitat house, a one-zone hydronic setup run off a water heater works great even in cold climates.
Dramatic thought #2: The cost of Warmboard.
Dramatic thought #3: How inexpensive it is to lay down 3/4" of plywood on top of an existing floor and router 5/8" tube groves for an effective Warmboard substitute. Heck for existing floors it's better since it's thinner. Throw in an aluminum reflector under the plywood if you want, but moving the tubes to just under the carpet pad/wood floor will make a large improvement in how fast a room heats up. Of course that only works well if you can put up with a 3/4" higher floor.
~D
I do like the Warmboard features, but now I am leaning towards 3/4" hardwood (some species with good stability) so I can't justify adding another 3/4" in height plus the added cost vs improving the tubing that I already have. I believe from what I have read and other posts that adding the heat transfer strips and some foil insulation will greatly improve on what I have currently. What do you think?