Modular Radiant Panels in Custom Modular Home

Constantin

Warmboard is very thick (1.25", IIRC) and a great way to get radiant into a home. With the right insulation package, you'll be comfy and save energy at the same time. As Warmboard includes a sub-floor, no further sub-floor is needed.

I would use the boiler to make the hot water for the radiant system and to heat the DWH. If you go with a gas-fired system, opt for a modulating, condensing boiler like the HTP Munchkin, Viessmann Vitodens, Weil-McLain Ultra, NTI Trinity, Buderus GB142, etc. Size the boiler to meet the maximum expected heatloss, then allow its modulation to save you even more money.

Instead of a tankless unit, I'd pipe the boiler to supply an indirect hot water tank like a 40-50 gallon Superstor. Given that your boiler will likely be too small to cover the demands of a continually-running shower, the indirect tank will act as a buffer and stretch the water supply to keep everyone happy.

If you have a very large dump load (like a jacuzzi) or very high-flow showerheads, then a buffer tank is pretty much mandatory unless you want to size the heating equipment to meet the hot water load instead of the expected heat loss. A large buffer tank is usually the more economical choice.

Check to see if PEX is allowed for potable water use in your area. Call the inspection department at your local town hall to be sure, as MA just allowed the use of PEX, for example.

Check out launstein.com for information on using hardwood flooring on top of RFH. Many installers here have had no issues as long as the wood was properly seasoned before installation (i.e. low water content), the planks weren't too wide, and the wood was quartersawn. I have 2" wide oak strips in my home and nary an opening anywhere.

You will find Radiant to be very comfortable. Zoning requirements are more a function of other people's comforts than even heat, etc. in a well-built home. For example, in depths of winter, we had the third floor "off" for a while (until the thermostat was installed) and despite what people tell you, the heat didn't rise from below to meet the demand upstairs... it was a good 10 degrees colder up there.

Plus, if one person consistently likes more heat in a room than the rest of the zone, you can always turn up the flow in that room while turning down the supplies to the rest of the zone by manipulating the valves on the manifold. Naturally, this is a bit more cumbersome than having multiple zones, but it's also a lot cheaper. However, your PEX has to be installed so as to allow the adjustment of flow to individual rooms... i.e. you shouldn't share a PEX loop across multiple rooms.

We planned for the future by embedding wires for T-stats in the walls that go back to the manifold. Should micro-zoning become necessary, the 110VAC outlet in the manifold box + the Tstat wires will allow each bedroom to be heated to its occupants wishes. Putting an outlet into the manifold box is cheap, as is running the T-Stat wires.

For a KISS solution that may or may not pass the aethestic requirements of the Boss (a.k.a. wife), look into the Danfoss FHV valves. They are TRVs that work great with the large tubes found in Warmboard and a very simple way to ensure that every room can have its own temperature. Cheers!

RGW

Modular Radiant Panels in Custom Modular Home

We are in planning stages of a two story custom modular home with full basement and usable attic space and radiant hear was suggested to us. Is thermalboard or warm board available (recommended) in modular homes? Any other efficient dry installation or radiant heat recommended. It appears that standard flooring is 5/8" osb--which can be upgraded to 3/4"--is osb or plywood better for this type of application

Could a boiler be used for the radiant heat and on demand for other hot water needs or is that an unnecessary added expense.

Modular companies seem to use PEX generally for regular water distribution--since a radiant floor will use PEX should entire system be PEX or should cooper be used for regular hot and cold water supply--especially if master bath is designed with high water use shower (multiple sprays and steam)and whirlpool (maybe an auxilary on demand heater is a good idea for the master bath?)

Is there any limitation on hard wood flooring or carpeting. Is it easy/cost effective to have more than two zones (ie each bedroom and major rooms)? Is this just a function of separate homeruns of the pex back to a distribution system

Many thanks.

RGW

Paul_41

Modular Homes

Please don't buy a modular home. As a volunteer fire fighter, please buy something, anything else. Having been involved in a couple of small and large fires, their performance in a fire is stunningly bad. While poor construction and questionable structure can be found anywhere, it is the rule, not the exception in modulars.

Mike T., Swampeast MO

Very Interesting Paul

Do they "come apart at the seams"? Problems with trusses? Rapid flame spread near joints?

Ragu

RGW: Modular Homes

Paul may be on to something. My personal experience in dealing with modulars (as a heating contractor) is as follows, and I mean it.

1) In our area of Maine, there is little cost difference between a conventional stick-built house and a modular. The "savings" appear to be that it takes less time from start to finish for a modular.

2) Philosophically, I believe that factory-built modulars take work away from local contractors, and keep money out of the local economy.

3) I have seen very poor mechanical system workmanship in modulars, where the modular dealer provides a "turn-key" service, using his usual sub-contractors. You will be much better off (should you go modular) to retain your own sub contractors.

4) Every time I do a modular job, I say "never again!", because the EXTREMELY FEVERISH jobsite work pace is just plain not conducive to producing a quality job. These things have become commodities around here; volume and quick turnover are the name of the game, and it can show.