Radiant floor heat, forced air heat or both? 5

[dancordle5360]

I am designing a 7,500 house with hot water radiant floors. I have specified approx 300MBH boiler. The architect has specified "Warm board", which claims to increase the response time to heating the house. Now the architect is suggesting that I put heat in the air handing system also. Do you think I need to or is the radiant floor sufficient.

Thanks

 

[walkes]

I am doing a similar house on a smaller scale, I am incorporating a hydronic heating coil in the air handling system for make-up air purposes. My intent is to ensure that the air is tempered to 70°F at the discharge when exhaust fans (or HRV) are running.

 

[GMcD]

Without knowing where in the world this house is, it's pretty hard to make any comment about the boiler size, heating requirements, HRV or ERV efficiency and whether additional touch-up heat is needed in the ventilation air supply. If this house was in the Canadian prairies somewhere, then yes, additional heat in the HRV ventilation is needed for defrost cycles and to make sure there is an added little extra for those peak winter conditions.

The first step is to design the house envelope properly and reduce the heat losses as much as possible. Something that house architects and contractors generally have no clue about.

 

[Drazen]

In any case, if quick response is strict client's requirement, you should reconsider use of radiant heating, no matter how comfortable and energy efficient it can be, as there is nothing as inert as floor heating, and some additions would carry little sense, redundant system for house would certainly be overkill.

 

[cry22]

redundancy is not achieved regardless. If the boiler or the pump fails, the AHU coil will not get HW. Unless one punctures the Radiant heat tubing, which is a long shot.

 

[KiwiMace]

If it is the heating system you refer, not just ventilation.... I don't see any good reason for complementing with some form of air system - half the enjoyment is the silence. Glassy areas might feel cool with radiant floors but this should be zoned separately.

 

[dancordle5360]

Thanks to all:

This house is in South Jersey with reasonable construction materials. I am not incorporating an HRV, and the exhaust is not extremely large.

Dan

 

[317069]

"Now the architect is suggesting that I put heat in the air handing system also."

do you mean that the air system is already existing in this design(if yes, what for?)or he wants to add duct system to hydronic system to justify his warm board?

 

[GMcD]

A house (the people in it, actually) needs ventilation, the tighter the envelope, the better. If you are using exhaust fans in the house and have no "air system" - where does the make-up air come from?

If the house is built tight, and then if there is no make-up air system, outdoor air will be drawn in through every little crack it can find in the envelope - in an uncontrolled manner, which in winter time leads to moisture condensation at the cold spots, then mold. If you have bathroom and kitchen exhaust, you need a source of controlled make-up air. Normally if you can supply all the heating needs from the radiant system, the usual method is to provide an HRV or ERV to provide the necessary house ventilation (exhaust and make-up air). And in colder climates, even the most efficient heat recovery unit will need some touch-up heat in the supply air.

Sounds like someone needs to take a good look at the "house as a system" here and sort things out.

 

[317069]

I remember one day I heard someone said something like "a Natural Ventilation" or somthing like that, can anyone explain please.

-what the difference between a regular house and an intensive care room.
- don't forget to provide a special treatment plant to your HVAC system because of pollution, an Oxegen source for emergency, an electric generator to keep HRV runing, and don't open doors when you go out or come in your house.

- if you want to prevent infiltration, you could delet windows and use electrical lights or candles instead.
sound like someone living inside....

 

[chicopee]

The air handling unit could be for an AC system.

 

[willard3]

I'm with chicopee, the only use for an AHU may be for cooling. It could also be used to preheat OA in winter, but the radiant system will be waaaayyyy more than adequate to heat the house and the thermal mass obviates most short-term heating problems.