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  1. #1
    Join Date
    Dec 2008
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    90

    Hydronic retrofit as a fix for badly done Nuheat mat??

    Hi, Folks!

    When we spec'd out our semi-custom house, we asked for heated master bath and kitchen tile floors.

    Well, we got 'em ... but they're only partially heated. The 'design center' assumed that we'd want only 'traffic areas' heated, in both rooms (in truth, we didn't even get that).

    It really stinks. Cold feet while doing dishes, cooking standing by the kitchen island, using the toilet (different room, obviously ), etc., etc.

    Our builder ... as it has turned out ... really IS a good guy. He's offered to give us "enough $$" to have a hydronic system installed, under the two rooms, using:

    • 40 gallon electric water heater
    • Taco pump with zone control
    • Electric thermostat
    • Caleffi manifold components
    • Amtrol expansion tank
    • Oxygen barrier pex tubing
    • Copper manifold components


    I have a couple of questions that I'm hoping to get some help with:

    1. The bid included a caveat, "The floor will only be warm when the system is running. If the thermostat demand has been satisfied, there will be no heat going to the floor." Does that mean it will get significantly cold, and we will clearly feel it cycle?
    2. The house is a ranch w/a full basement. In this sort of application, is a programmable thermostat a good idea? I know that, in slab-on-grade, it's not advised to use setbacks....
    3. If there IS a gap between setpoint being achieved, and call for more heat, could the Nuheat system be used to provide bridge heating??
    4. I assumed the Nuheat system would be fairly bulletproof and very long lasting. Are there significant lifespan and/or maintenance requirements and/or $$ for the hydronic system (eg, It seems that glycol has to be checked annually, and additives may have to be added, etc.)
    5. Is it common/normal/alright to use what seems to be a standard residential water heater to support such a system? We're looking at heating a 17x11 kitchen and a 10x10 master bath.
    6. Any other thoughts on this switch-over??


    I'd be grateful for the help.....

  2. #2
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    1,974
    Some questions to clarify what you wanted, what you got and what you expect when any changes are made.

    Originally you wanted warm tile floors?

    Were these warm tile floors expected to heat the kitchen and bathroom without any other means of heat, or is there another heating system in the home?

    Were the specifications in the original contract vague enough that a professional would have understood them to mean you didn't want all of the exposed square footage of tile in question warm?

    Are the areas under both floors fully accessable?

    Searching your previous post(s) I see where this isn't the first issue you've had with this builder. Maybe it's time you draw the line with living with what seems like the builder's (and his subcontractors) tendancy to push the limit with what they can get away with.

    As far as using a water heater for a heat source for a radiant floor warming system, check with your local code enforcement department and see what they have to say about whether they will approve of this.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  3. #3
    Join Date
    Dec 2008
    Posts
    90
    Thanks a bunch for the reply. Answers....

    Quote Originally Posted by firecontrol View Post
    Some questions to clarify what you wanted, what you got and what you expect when any changes are made.

    Originally you wanted warm tile floors?
    Ayup. Exactly.

    Were these warm tile floors expected to heat the kitchen and bathroom without any other means of heat, or is there another heating system in the home?
    The warm tile was to allow us to use travertine, in those two rooms, without it being freezing cold in the Northern Colorado winters. The floors are above a conditioned, but unfinished, basement. The house is heated/cooled with a Carrier Infinity system w/96AFUE furnace, 21SEER a/c, Lennox HEPA filter, and a Honeywell TrueSteam humidifier (not hooked up properly (for fully automatic humidification, tied to outdoor temp) and currently inoperative (HVAC guy comes Wednesday )).

    Were the specifications in the original contract vague enough that a professional would have understood them to mean you didn't want all of the exposed square footage of tile in question warm?
    Very fair question. I believe our initial request was for "heated floors." It translated into "in-floor heat system," on the Contract. The (NOT builder-affiliated; a local retailer) Design Center went over every other option (all hard surfaces) in great detail. The floor heating was never discussed.

    Are the areas under both floors fully accessable?
    My guess would be yes. I'll have to have the proposed contractor out to verify. There may be plumbing and electrical running between some of the relevant joists, but -- since it's new construction, a full basement, and an unfinished basement, I'm assuming access will be pretty good.

    Searching your previous post(s) I see where this isn't the first issue you've had with this builder. Maybe it's time you draw the line with living with what seems like the builder's (and his subcontractors) tendancy to push the limit with what they can get away with.
    Sigh.

    True enough, but ... despite mistakes ... they continue to try hard to make things right. For the moment, I want to be very careful that neither of us digs our heels in. The builder is run by a young (30's?), bright guy who's generation #3 of a 55 year-old local company.

    As far as using a water heater for a heat source for a radiant floor warming system, check with your local code enforcement department and see what they have to say about whether they will approve of this.
    I'll do that. Assuming no Code issues, do you think there are any practical reasons to worry about this approach?

    I'd be grateful to know what you think, based on the above....

  4. #4
    Join Date
    Dec 2008
    Posts
    90
    Let me add one other thing, if I may:

    I have a concern that the water heater being referenced is sort of your $259 Sears job.

    When I look on websites dealing with hydronic heating, what I see are "indirect hot water tanks" that seem to be of an ENTIRELY different level ... like ... this guy.

    That's part of what I'm trying to figure out: are the hot water demands of a hydronic system substantially different enough that a "pure" hydronic-designed boiler or indirect model NEED to be used?

    Thanks again!

  5. #5
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    1,974
    Practical reasons to worry? ............... Impossible to answer without physically seeing what you have.

    Hot water radiant heating systems installed under subflooring that is designed to heat the surface above to a warmed floor temperature (not for heating the room) has it's own limitations. If not installed correctly it won't give you any more satisfaction than what you have now. What I'm trying to say is that it's not the kind of installation that performs well with "close enough OR that should do it" methods. This needs to be designed to the "T" and if the numbers say it may not work, it shouldn't be attempted.

    Under the subfloor installed radiant floor warming sometimes requires very hot temperatures of water. The efficiency of converting electricity to hot water to warmed subfloor boards to tile is not going to be as cheap to operate as the originally used product and could, depending on the installation could cost substantially more.

    With a 4500 watt element in the standard electric water heater and the potential for it to be on 24/7 depending on the installation, control and dozens of other reasons, the cost to operate this could be substantial. 4500W / 1000 = 4.5KW ... 4.5KW x your cost per KW from the electric co. x 24/7 x 30 days I'm to scared to do the math!

    Of course this train of thought is worse case scenerio, but ......... you're already dealing with a situation where you installed expensive tile with I'm assuming a not so inexpensive floor warming system expecting for it to be comfortable with something less than boots on to live with. Maybe a normal pair of shoes in the kitchen wouldn't be a big deal, but they might prove unhandy in the bathroom.

    Sorry..... I hesitated to comment on this thread to start with because it's one of those where I'm not there, don't know all the details (and no way I ever can) and know from experience there are all sorts of ways to deal with it..... none of which I can fully nor intelligently comment on without being there.

    I guess I don't see this as you "digging your heels in" but instead you are wanting what you started out wanting. You didn't get it. They didn't supply it. And now they're offering an option that "I" would be suspect of due to their track record.

    Maybe an option is that you agree to their installing this system to "fix" the issue with the following conditions.
    1) They guarantee (in writting) the installation of the alternative/backup system to satisfy your original request for warmed floors over the entire square footage of both floors.
    2) They guarantee (in writting) that if through time testing and documentation, the alternative heating system costs you more to operate than the estimated cost to operate the original system if it had been installed under the entire floor, that they will pay you the difference for ........ say 10-15 years. That's my guesstimate of how long the Nuheat floor would last or the amount of time before you'd want to change the tile and could them upgrade the original system.
    3) They guarantee (in writting) that they will personally warranty the entire new system for the same amount of years as the Nuheat system is warrantied for.



    It's not a perfect world no matter what anyone tells you. Least you should get for your money is what you feel is as close to what you want as you deem sensible.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  6. #6
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
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    Quote Originally Posted by NBeener View Post
    Let me add one other thing, if I may:

    I have a concern that the water heater being referenced is sort of your $259 Sears job.

    When I look on websites dealing with hydronic heating, what I see are "indirect hot water tanks" that seem to be of an ENTIRELY different level ... like ... this guy.

    That's part of what I'm trying to figure out: are the hot water demands of a hydronic system substantially different enough that a "pure" hydronic-designed boiler or indirect model NEED to be used?

    Thanks again!
    What would be more appropriate, in my opinion, would be to use a fully modulating electric boiler of appropriate size. For example....... this unit:
    http://www.thermolec.com/boilers.htm
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  7. #7
    Join Date
    Dec 2008
    Posts
    90
    firecontrol:

    Thank you so much for your responses. The things that you don't know, I surely don't know, either. Your responses are thoughtful and helpful, and absolutely match up with the concerns I've had.

    The worst-case scenario -- using actual numbers -- comes out like this, in my spreadsheet:

    HYDRONIC / Nuheat
    heating element watts 4500 / 1,232.4
    kilowatts/hr 4.5 / 1.2324
    $/kw-hr $0.0668 / $0.0668
    kw-hrs/day 24 / 24
    days/mo 30 / 30
    htng mo/yr 5 / 5
    cost/day $7.21 / $1.98
    cost/mo $216.37 / $59.26
    cost/yr $1,081.84 / $296.28

    But, that DOES assume 24/7 operation, for EITHER system -- something that doesn't sound realistic, to me. Is there any way to take a WAG at a % of the time that the hydronic system's water heater might, realistically, be operating??

    I run the basement at 60F, but (and maybe this is how I should have approached it, all along) ... my system is zoned, and I could just as easily run it at 65F ... or whatever.

    The warranty issues you raised are EXACTLY as I discussed them with my wife: it's his right to take this shot at fixing the problem, but ... if it doesn't work ... then I see no option besides the nuclear option (gut the two rooms, re-do the floors, properly, and put everything back together).

    Giving me $X, based on potential for increased operating costs -- hydronic vs. electric -- reduced by some net present value calc -- was another thing I thought of. I can easily find out the total wattage of a Nuheat floor, done right, that would have covered every tile, and do the math from there.

    I REALLY appreciate your willingness to chime in, here, with so much absent info. Are there any particulars that I COULD get that would enable you, or others, to hone in more??

    Also, is there a particular reason that a boiler like you suggest makes dramatically more sense, in my situation, than the "Sears electric" that I referenced -- even in general terms?? I don't understand the basic difference between these boilers and a basic domestic hot water heater well enough to hazard a guess....

    Again, my thanks!

  8. #8
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
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    You could put each of the floors on a setback thermostat or timer that would only allow for them to run for a certain amount of hours a day. You'd have to learn how much lead time you'd need to get them to a comfortable temperature before your anticipated use. This would (if you figure full time ON) give you a more accurate baseline.

    How much each would actually run is anyones guess. Calculations can be done with every little bit of information known, but it still comes down to how the actual system works to know for sure.

    The difference between the boiler and the water heat is that one was designed, built, tested and certified to do what you're wanting to do and the water heater wasn't.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  9. #9
    Join Date
    Dec 2008
    Posts
    90
    firecontrol: my sincere thanks, again, for all of your help, here.

    I just had a lengthy conversation with the contractor who provided the Proposal. After discussing what I have, and what I wanted, his answer was quite simple: you'll spend LOTS more money operating an overly complicated system that adds a small truckload of junk to your basement.

    Have the builder rip out the tile, and re-install the mesh throughout both floors, to get edge-to-edge coverage.

    I can't be sure if that's the way this will go, but he pretty much supported all of your points, and THIS was the guy who stood to profit! I'm always impressed when somebody has the decency and integrity to tell me that -- while they'd be happy to sell me something -- it really isn't what I need.

    Thanks, again!

  10. #10
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
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    There's a contractor that you might want to seriously considered recommending to your friends!
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  11. #11
    Join Date
    Feb 2003
    Posts
    1,996

    Temp variations with the NuHeat

    The hydronic floor warming will always be at a different temp then the NuHeat.
    I'd shut off the Nuheat and tube the whole area under the tile floor. I would have a timer in the winter months to circ the water in the mornings and at night.

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