Have Radiant heating - need supplemental heat ?

[UpstateNY]

Guys,

Just finished installing a radiant heating in-floor system (natural gas based), concrete will be poured in a couple of days. It's cold here, but with the radiant heat operational, the pour will occur over heated Pex .

My question: do you guys that have radiant heat in your shops use an auxilliary heater to do a "quicky" warmup while the radiant ramps up the heat ? I'm thinking before the pour running some 3/4 iron pipe in the slab and stub it up near my work area. Then, down the road, I could install a ventless NG heater to take the chill off quickly.

BTW, it's a 30' x 40' build. Thanks for any opinions.

 

[GYPSY400]

Its not really necessary if the system is sized properly.. the heat recovery is about 5 to 10 minutes after the door is closed. I have the pex installed in my slab but im doing a reznor first.. then down the road im adding a solar heated hydronic system.

Sent from my SGH-I747M using Tapatalk

 

[UpstateNY]

Gypsy,

Thanks, but that wasn't the scenario I was envisioning. I realize if the radiant heating is turned on, and the floor is warm, that the bldg will recover quickly if a door is opened.

My scenario is: the bldg is cool, say 45 degrees, and has been all week, the radiant is "off", it's Friday night and I decide I want to work in the shop, so I turn on the radiant, but the heat takes a while to produce. Hence, the idea for a ventless, NG heater to get some quick heat "now" while the radiant comes up to speed.

Since I'm only doing the pour tomorrow, and the bldg is not yet insulated, I'm asking for the experience of others. Do folks in the colder climes, with radiant heat, find the need for supplemental heat ?

 

[tdkkart]

My question: do you guys that have radiant heat in your shops use an auxilliary heater to do a "quicky" warmup while the radiant ramps up the heat ?

Answer: The most efficient way to run radiant floor heat is to run it the same temp all the time. A 1200sq/ft floor contains approx. 15 yards, or 50,000lbs of concrete, you cannot bounce the temp of that much mass quickly, nor do you want it to cool down. Concrete radiant floors are intended to be turned on in the fall and turned off in the spring.

The one thing you will find with radiant floor is that you don't have to run the temperature nearly as warm to be comfortable. In the past I have had a forced air shop that I had to run at 65-70* to feel comfortable, and even then my feet were always cold. Today I have the thermostats in my shop set at 54*, I work dressed in a T-shirt with a loose flannel shirt over top, any more than that and I am sweating.

 

[jlckmj]

You could mount a supplemental heat source. I would think that turning your slab up and down would be counter productive. I find that one set temperature works best. Set it and leave it.
I would be interested to find out how hard your inn floor source would have to work in order to bring it back up to temp. vs. leaving it alone. Then weigh the cost of the supplemental source to the cost of raising and lowering the temp.

My floor source (gas water heater) only cycles 3-4 times a day for 15 to 20 minutes at a time with a 10* outside temperature. Letting the slab get 20 degrees lower would mean running it for a at least a couple hours to bring it back up. I think it would be a wash money wise to do that.

One positive about the supplemental source would be if your main slab source takes a puke, you would still have heat.

Jim

 

[Thumper68]

I have a programmable thermostat in the shop and during the week Sunday midnight to Friday noon it keeps the shop at 50*. At noon on Friday it ramps the heat up to 65* where it stays until Sunday midnight.

Radiant or hydronic floor heat is most efficient when set and left at a certain temp unless like in my case I rarely use the shop during the week and letting it cool down and then heat up for an extended time is okay too. If I am going to be using the shop during the week I will just hit the hold button on sunday so it will stay at 65*.

Another point I turn the heat on in late Sept. before I actually need the heat it keeps the floor warm at night so I don't have the added expense of having to warm the floor from 40* or less.

I do have 2 elec. ceiling mounted radient heaters in the shop but rarely use them one is in the area where I work on electronics and the other is over the miter saw of those I only use the one over the electronics area when I am sitting still for a long time, keeps my finger warmer for the fine control that's needed when fixing circuit boards etc..

 

[rburke65]

To answer your question....spend the little money for the gas line and you will have it if YOU think you need it. If everyone else is warm and toasty, and you are cold, who are you concerned about? Not THEM. Run your gas line.....cheap assurance.

 

[UpstateNY]

Guys, thanks for the thoughtful responses.

My (water-heater-based) radiant system is located in the "front-left"corner of the bldg. My car lift and primary work area will be in the "back-right" corner of the bldg.

That said, I think I'll forego running the gas pipe to the back-right corner area to have for a supplemental ventless gas heater, should it be needed. All of my electrical, water and gas utilities are clustered tightly in the front-left portion of the bldg (where the overhead doors are). If I do need a supplemental heater, I think I'll install it in that front-left area, that will keep all the mechanicals in one place and leave all of my remaining wall space open for benches and stuff. Since I have 5 ceiling fans in the bldg, I think/hope they'll move the supplmental heat around quick enough to take the chill off in the event the radiant heat needs time to come up to temperature (I don't know what temp I'll be keeping it at).

If I need suplemental heat, part of me wants it near me for quick and toasty heat, the other part craves organization and safety, and having it clustered with other utitility stuff will alleviate the concern over keeping things away from the heat source back in the work area. Although, I may forego a bit of instant-heat by doing so, it gives me the most freedom and safety.

Worse case, I could surface mount the gas pipe if I find I need it in that area. Good thing is I over-engineered the radiant system. I installed 5 loops where 4 would've been sufficient. So I'll be able to pour beaucoup amounts of heat into the slab.

 

[theoldwizard1]

Its not really necessary if the system is sized properly.. the heat recovery is about 5 to 10 minutes after the door is closed.

Well, that depends on a couple of things

• How big is the door ?
• How long is it open ?
• What is the temperature outside ?

A double wide 12' high door makes a very big hole and an opener will take some time to pen and close it. A single wide, 7' door, manually operated is a whole different story.

Same with the outside temp being 40F, 20F or -20F !!

 

[Highbeam]

You will want a second source of heat unless you plan to constantly heat the shop to "working" temps. The radiant will do the bulk of the work keeping the building above freezing and then the short term bumps can be handled with your secondary source.

A hobby shop is really a pretty poor place for a radiant slab as your only heat source. It takes so long to heat up the slab that you need to have it warm all the time. That wastes energy.