What are the pros/cons of radiant floor heating?

[Wild Turkey]

Getting into final stages of planning my shop.

We have generally mild winters here (although it's below 20 degrees this week
) but I've been wondering about the advantages of radiant heating.

I assume you can still use a heat pump system as the source.

My thinking is that the mass of the floor would keep the heat/cool cycle evened out and reduce rust on the machines and moisture changes in the wood.

Anyone use one?

[Robert Adams]

Fist off you need a boiler or other form of waterheater. A heat pump could be rigged in a way but it just can't do the heat output in btu and can't do the higher temps needed for radiant even before you figure the losses of converting heated air into heated water. There might be a unit made for hooking up to a heat pump and getting it to heat water but I have never seen it. 

       KY is much further north than us and your winters must be pretty warm. It's 12* as I write this here in Fort Worth... And heat pumps don't work well here. My parents usually have to switch over to emergency heat when it gets below 40 unless they want the heat pump to never shut off( well run for a very high duty cycle)... 


            For shop use radiant is a poor choice. You can't just turn the heater on when you want it warm. You have to maintain the temp consistently and if it's a slab you really have to slowly warm it up.  In a house it's an issue as well because your house will now be at a constant temp. We like to turn down the temp at night as its more comfortable to sleep when it's cooler. So radiant can't do that. 

       Being that you have to keep the space essentially a constant temp it makes it comfortable but can actually cost more in energy in some cases. 

     In the hangars and other shop areas I have been in with radiant heating it has been  uncomfortably hot on the feet because of the higher floor temp needed to heat a larger volume area than say a house as the ceilings are generally much higher than a house. 


       As for the rust on tools there shouldn't be an issue either way unless you are using direct unvented flame to heat your shop. That would produce lots of moisture that would condense on the machines. Here the humidity is high year round.   It's now 10* on my weather station and the humidity is 73% which is backed up by another station here... Basically if your tools are getting condensation and rusting in the winter something is goofy as I should have more of an issue and I dont.  


         As for the upside. Your feet are warm and you will be more comfortable in the shop with radiant heat. That's about it for the upsides.. 

         Don't get me wrong I really like radiant but it has its issues. I'd love it in the house but I would either zone the bedrooms much cooler with forced air to warm it in the morning or only have them as forced air.

          Oh forgot to mention that going from forced air to radiant makes your house dirtier and dustier. You no longer have the second biggest air filter in your house. The biggest air filter in a house is carpet hence why houses with no carpet are full of dust, hair etc. They don't have the carpet to catch a hold it until the vacuum picks it up. (Yes we have mainly hard floors and I hate them as they are cold and uncomfortable to walk on barefoot along with the other issues)

[crokett™]

My parents usually have to switch over to emergency heat when it gets below 40 unless they want the heat pump to never shut off( well run for a very high duty cycle)... 

then your parents have an inefficient heat pump and should get it checked or replaced with something that has a higher SEER rating.    I have two of them.  They do just fine at 40 degrees.  I don't start worrying until temps get below the upper teens.

for the OP, what was already said about radiant floor heating. If it were me, I'd be taking a look at a min-split.

[Robert Adams]

then your parents have an inefficient heat pump and should get it checked or replaced with something that has a higher SEER rating.    I have two of them.  They do just fine at 40 degrees.  I don't start worrying until temps get below the upper teens.

for the OP, what was already said about radiant floor heating.  If it were me,  I'd be taking a look at a min-split.

       It's a 14 seer that was new in 2010. The issue is the extremely long run times with it. It's still working properly last I checked and they had the owner of the hvac company here look it over while I was out of town last year and couldn't do a spring check on it. They are just stinking slow at heating. It'll freeze you in the summer if you want it to and no the reversing valves aren't sticking. They would just prefer the shorter run times of straight electric heat. They have had space heaters going all night as the emergency heat isn't enough to heat the house when it's this cold either. Was under 20* all night and 9* this morning. Have already got the supply house getting a larger em heat coil as this comes up a couple times every winter.

[fredhargis]

Robert pretty much covered everything I have heard about it. I think Bloomington Mike put in that taj-ma-shop he built, but his needs/use probably exceed that of a hobbyist. To be honest, I don't like forced air heat in a shop...but to me it's about as convenient as it gets. Reasonably low install cost, reasonable operating cost (at least for me...good insulation, even though I use LP), and quick recovery time. But at you latitude it might be worth looking at a mini-split, that would give you AC as well. I doubt anything you choose will have a significant effect on the moisture levels in your wood.

[fixtureman]

The shop I worked for had radiant heaters that worked very well

[Wild Turkey]

Good points. Looks like a mini-split is the plan.

I hadn't thought about the dust/dirt problem with hardwood floors. May have to rethink some house plans!

Thanks for the help.

[jteneyck]

Good points.  Looks like a mini-split is the plan.

I hadn't thought about the dust/dirt problem with hardwood floors.  May have to rethink some house plans!

Thanks for the help.  

I'm not advocating you install radiant heat in your shop.  Just thought I'd tell you of my experience with it.  I have it under my kitchen and sun room floors and it's nothing but great.  Had it for almost 25 years.  The water temp. is tempered to 80F in the kitchen because of the bamboo floor.  It is not hot on your feet, nor was it even when it ran at 130F with the old tile floor, but the room stays a nice 72F.  You would need someone to do the heating calculations to see what temp. you would need to run the slab at to maintain whatever ambient temp. you wanted, based on typical and worst case temps. and the building insulation, etc. 

From my perspective dust is a non issue, and certainly wouldn't be a deciding factor on which heating system I chose. I hate carpeting. I vacuum now and then. It's no big deal.

If you are doing a new build I think it's worth your time to run down the details before deciding which way to go.  

John

[crokett™]

What temperature do they keep the house at and how old/well insulated is the house. My heat pump has no problem maintaining 70 degrees in temps down around 20. Sure it runs longer than at 40 but that's expected. I'd keep the thermostat at 65, but I lost that battle long ago.

[Stwood_]

I've been in several truck shops that had radiant (floor), and worked in one of them.
They sure are nice. Heat recovery is fast after raising the overhead door and bringing in a semi.