Fears about new construction with radiant heat flooring

Alan (California Radiant) Forbes

I just went to a house with cork floors over radiant heat. The tubing is in light weight concrete and our winter temperatures are mild which means the temperature of the heating water will be low, but I still think cork would work well at your house.

hot_rod

What is also interesting is to lift up those throw rugs and see how much warmer the floor surface is below them. An infrared camera really shows that also.

It is still by far the best way to add some "rug" to radiant floors, it does change the output a bit.

Solid_Fuel_Man

We have a 1/2" thick wool throw rug in our liv8ng room. Rug is 8x12 and the radiant slab is warm 20 hours after any heat input. 7" thick slab tubing 4" deep, 2" xps below.

Henry

The number one question is who designd the piping setup and loops? We have Wisbro design the loops. They give us the flow rates and BTU requirement. One cannot just lay tubing down on the floor! This project would of been some much simpler if a proper heating contractor with experience with radiant heating was involved. 95% of our radiant heating jobs are installed over the floor. Then covered with a self leveling thin coat. BTW you need a Thermolex B15 boile. I would put a B18 because you are "en campagne" and there is colder weather than the city.

john p_2

Alex, did you decide to use the Ultra Fin?

alexclusif

John, no I did not, reason being a) tubing was already passed in bays (2 per bay) so kinda defeated the purpose of ultra fin and b) one installer in our area had a couple stories with an almost identical product as ultra-fin but locally made, that made clicking or ticking noises under certain conditions...which I really did NOT want to have! Whole thing about infloor radiant is silence However, that being said, I think ultrafin is a really good product nonetheless and probably would not make any significant noise if properly installed. And I would have gone with it had the tubing not already been installed.

Henry, we will be using a Thermo2000 15kw boiler which is wayyy plenty considering my heat loss calc demanding only 8kw. My buddy works there (local factory) and they are very well renowned and well rated from what I hear from others. Just hope all that overkill isn't too damaging to my heating bills. Though a smaller boiler would probably work harder and negate most savings anyhow.

As updates go, the boiler installer is way more knowledgeable than the building contractor who passed tubing etc thank goodness. Believe it or not he had the tubing rubbing up against some aluminum staple plates holding the joists together which is a total no-no! Good thing boiler dude noticed and we fixed that. We're also a bit concerned about zoning because contractor did 1 zone for bedrooms and 1 for rest but considering 1 bedroom is south facing with huge window and 1 north, will be interesting to see difference on a cold winter sunny day! That's gonna demand a very smart thermostat! haha
As is, contractor stapled up aluminum foil, and 6-8 inches of cellulose under that so at least it will be insulated from below. My one question though is : is it normal to have all the wiring of the house and ducting for HRV all mixed up in there? Won't the high heat demand affect that stuff in the long-run?


We will be moving in only in March so won't be seeing much use of system this year I believe. Today was a sunny 19 degrees F outside and inside house was 80F with just a single 4000w contractor heater set at 70F!! I Think we may have more concerns with cooling than heating in the long run! In any case, anxious to see the sytem working and will keep you all updated for sure.

Alan (California Radiant) Forbes

I'd reconsider that oversized boiler. Even though it's electric, I think oversizing will have it's drawbacks.

Solid_Fuel_Man

I agree with Alan. Why? Just get an 8kw or 10kw. The larger will cycle, which won't actually cost you more to operate, but may prematurely wear out the SCR'S that control the elements. Hopefully it's not a contactor.

alexclusif

Well I have a friend that works at Thermo2000 a company that builds these things and he managed to find a boiler that he reconditioned and it just so happened to be a 15kw but it was dirt cheap so couldn't pass on it.

MikeG

Aren't most of these boilers staged with multiple elements? I would think that this would limit the short cycling. I don't know the control strategy but it may just put more hours on a few elements.

Lance

Lots of variables apply. All must be taken care of. Principles to follow: Cycling rate vs temperature swing vs insulation resistance vs material affected. Different forms of radiant installations are used for different applications. In floor, staple up, plate in air, tube in concrete, below, above etc.
Open joist space is great for plate type systems where higher temps can be applied that keep floor temperatures proper and still provide maximum fluid BTUH delivery.
In floor sensors are important to better respond to the natural delayed response of radiant. I have used four different radiant installation techniques in one home. In wood slot under tile, in concrete, in joist space with plate and staple up. All work differently but all work well as each is applied to match the floor situation. Pipe and controls alone make a difference. remember water in and out makes no difference if the surface convection and radiant transmission is wrong. Took me 10 years to get decent at this and another 10 to perfect it. And still they keep changing this stuff. Even a throw rug can change things.

Alan (California Radiant) Forbes

I retract my statement and MikeG is correct. Spoke to a Thermo 2000 employee who said there are 4 staged elements in the 18kW model; more elements are energized the greater the load.

When you start having children and want to double the size of the house, your boiler will be ready.

Don't know if the elements are set up for lead-lag.

Jackmartin

To begin with I am a Canadiam living in a really cold part pf Canada and we do not call boilers __boilers if they only produce steam.Where you are getting your information about Canada is wrong. Hot water tanks heat domestic water: boilers are steam boliers or hot water boilers. Now as to using an instant hot water heater for your radiant heating is INSANITY this is destined to leave you cold and paying an energy bill Trump could not afford. Your heat loss calculations have to incorrect in all my years even in super fart proof houses the kind you pass gas on Monday and still smell it on Saturday we have never had as low a heat loss summation.Thirdly electric boilers are bad news they have a very short life compared to gas or oil you are in for a huge dose of pain both monetarily and in comfort. Why did I apprentice all those years and then let my customer do his own design-- Well I would not be involved in a job where the home owner designs his own system unless he or she was a professional engineer. I would suggest you retain the services of a good heating engineer -- Yes we call them engineers just like in the USA strange considering how backward we seem to be -- and do exactly what they tell you to do and go to the bank and spend some money now.A little short term pain now is better than paying utilities that bankrupt you for the next forty years. Why do I say forty years ;anyone who wants to buy your house down the road will probably have it inspected prior to making you an offer,no one is going to buy a home that costs whats yours does to heat given Quebec's design temperatures. Jack Martin Winnipeg Manitoba

alexclusif

Jack, here's a link to a similar hot water "BOILER" we had installed. http://www.thermo2000.com/content/en-US/s2_produits/chaudieres/bth-ULTRA.aspx
Call it what you want, it's not an instant hot water heater. It's an electric boiler. I know propane would have been better, but around here it's electric all the way probably not in your part of Canada. Quebec = Hydro Quebec, so far cheap rates (rising but still...) and so that's what we all use here. That's what people sell, and know how to repair and do maintenance on. And Thermo2000 boilers are very rugged and durable. My friend who installed it has been installing them for years for that company and he assured me they are super reliable (as far as electric boilers go). I trust him completely. He is no engineer but he's great at what he does.
Just hope you are wrong about future heating costs!

alexclusif

Alan (California Radiant) Forbes said:

I retract my statement and MikeG is correct. Spoke to a Thermo 2000 employee who said there are 4 staged elements in the 18kW model; more elements are energized the greater the load.

When you start having children and want to double the size of the house, your boiler will be ready.

Don't know if the elements are set up for lead-lag.

Yup that is correct. Mine is actually a 15kw 3 element design but that's how they work. Thanks for checking that out

Gordy

I really see no problem with an electric boilers longevity in a closed system such as hot water heating. When quality fill water is used.