1947 raised cottage renovation

davejohnsonnola

1100 sq foot cottage on short concrete piers in southern humid Louisiana. This is the house I grew up in and plan to retire in. Currently 57 yrs old.

Want to upgrade HVAC in general and but need to soon replace a gas water heater anyway so thinking about incorporating radiant floor heating. Definitely like the idea for kitchen and bathroom floors as well as faster hot water at the faucets, but concerned about humidity and wood flooring.

Very short heating season. 2.5" original oak wood floors over 2x8 subflooring everywhere except kitchen and bath. Currently without underfloor insulation. Been getting by with window unit a/c and variety of electric space heaters over the past few years as the old gravity floor furnaces sadly passed away.

Since this will be a longer term project the a/c and general whole house humidity levels likely will not be addressed until later. Should I hold off on doing radiant heat until after a/c and humidity is addressed?

Jamie Hall

I'd be very very cautious about radiant heat under those oak floors. That's a lot of wood thickness to push heat through -- and there is also the consideration that it would dry the wood out a lot, which might give you some problems. Too much humidity is not a good thing -- but too little can be a problem, too.

I'd very seriously consider a whole house heat pump system -- it would run mostly as A/C, but can be changed over automatically to heat -- particularly as you have access (albeit I dare say a bit cramped!) under the floor. It could have the humidity control built in as well.

davejohnsonnola

I should edit the finish flooring as 2.5" wide, NOT deep, but yes that is where my concern lies. As much as I love the idea of warm feet, I cringe at the thought of ruining the wood flooring.

jumper

I'd look into those new Canadian CO2 heat pump hot water heaters. I'd gravity circulate that hot water to a ceiling panel. Maybe you can run it with solar electricity? Thermal storage. After heating season use that electricity to run a dehumidifier. Maybe the oak will store some drying potential?

Ironman

It appears from the wording of your post that you intend to use your water heater to heat the proposed radiant floor. If that is so, let me encourage you to abandon that idea. Doing so would create a large legionella breeding plant. It's long been outlawed in Europe, Canada and a lot of the US.

There's no cheap way to do radiant properly and you'd need a boiler or water side heat pump.

Considering the size of your house and your locale, I second what Jamie said about a heat pump system.

A multi-zoned ductless system (like a Mitsubishi) can be very comfortable and economical.

Also, a properly designed radiant floor is not warm to your feet: it usually feels neutral or slightly warmer.

Gordy

davejohnsonnola said:

I should edit the finish flooring as 2.5" wide, NOT deep, but yes that is where my concern lies. As much as I love the idea of warm feet, I cringe at the thought of ruining the wood flooring.

The narrow flooring is a plus as in movement, and shrinkage.

Rich_49

A water heater is just fine to perform space heating also so long as you tale the proper precautions . Using something like a Taco X pump Block or site built heat exchanger w/ controls would be such a thing .

Do not know what heat pump water heater jumper was talking about but Sanden does not recommend nor will they back up space heating with their Co2 heat pump, probably could be done however .

You do realize that if you do this you MUST insulate below the floor and tubing right ?

jumper

Water heaters are designed for 40° or 50° feed water but return water in heating systems is much warmer. That maybe a problem but there is probably a solution.

Rich said:

A water heater is just fine to perform space heating also so long as you tale the proper precautions . Using something like a Taco X pump Block or site built heat exchanger w/ controls would be such a thing .

Do not know what heat pump water heater jumper was talking about but Sanden does not recommend nor will they back up space heating with their Co2 heat pump, probably could be done however .

You do realize that if you do this you MUST insulate below the floor and tubing right ?

Ironman

Rich said:

A water heater is just fine to perform space heating also so long as you tale the proper precautions . Using something like a Taco X pump Block or site built heat exchanger w/ controls would be such a thing .

Let's be clear about a couple of things if we're gonna say a water heater is fine:
1. You're talking about a tank water heater, not an instantaneous.
2. A water heater does NOT have an ASME "H" stamp and is therefore not approved for space heating.
3. The Taco X Pump Block could work, but the expense of it + the water heater has put you near the cost of a small mod/con.
4. The secondary circulator on the X Pump Block may not be sufficient for a radiant floor looking for a 10 - 12* delta T.

Rich_49

Ironman said:

Rich said:

A water heater is just fine to perform space heating also so long as you tale the proper precautions . Using something like a Taco X pump Block or site built heat exchanger w/ controls would be such a thing .

Let's be clear about a couple of things if we're gonna say a water heater is fine:
1. You're talking about a tank water heater, not an instantaneous.
2. A water heater does NOT have an ASME "H" stamp and is therefore not approved for space heating.
3. The Taco X Pump Block could work, but the expense of it + the water heater has put you near the cost of a small mod/con.
4. The secondary circulator on the X Pump Block may not be sufficient for a radiant floor looking for a 10 - 12* delta T.

Just for clarity .

1. Of course I am . Why would I assume someone is talking about something other ? By simply looking at the documentation for a Taco X pump block one would know this .

2. The requirement for an ASME H Stamp is not universal , in fact water heaters can be used in more jurisdictions than not . Just because codes are slow to respond does not mean something is not fit for an application . Why do we need an H stamp device for a low temp application .
Do these have H stamps and would you say they are sufficient to heat a home ? Both are approved for use in a majority of this great land and are only prohibited in the most backward thinking large cities and some states that are a few decades behind the curve . We need to get over the thought that an heating system that requires low temp fluid needs a boiler .

http://www.htproducts.com/versahydro.html

http://www.htproducts.com/pioneer.html



3. Put us near the cost of a small modcon ? Don't forget the indirect , controls , buffer tank , LABOR . The math is not for us to determine . Why is it that we have a need to suggest other things when someone comes here ? Unless they have or have been given a TERRIBLE idea maybe we should just assist them .

4. I believe the X pump Block has an onboard 008 . Most installers screw this operation of pump selection up on ten regular . The only thing that determines what the system side requirement is would be a heat loss right ? Pretty safe to assume a system in NOLA would be easily handled at peak heating season . Considering that this exact set up is used frequently by experienced , do it right plumbers as far north as Northern Canada in well built homes and buildings .
http://www.taco-hvac.com/uploads/FileLibrary/102-202.pdf

No disrespect meant Bob , just to be clear .

Rich_49

jumper said:

Water heaters are designed for 40° or 50° feed water but return water in heating systems is much warmer. That maybe a problem but there is probably a solution.

Rich said:

A water heater is just fine to perform space heating also so long as you tale the proper precautions . Using something like a Taco X pump Block or site built heat exchanger w/ controls would be such a thing .

Do not know what heat pump water heater jumper was talking about but Sanden does not recommend nor will they back up space heating with their Co2 heat pump, probably could be done however .

You do realize that if you do this you MUST insulate below the floor and tubing right ?

They also bring tank temps back up from a differential when they've been on standby . I'd go way out on a limb to say that lower temp is over 100* .