Shop Heat

[Mark Blatter]

I started my shop a little over two years ago. I had it mostly completed by June or so of last year, but was busy and just didn't the heating system completed. All last winter I used a space heater, burning through I don't know how many tanks of propane. All the time, the on-demand water heater and the manifold was installed on the wall. All I needed to do was put up the thermostats and control box, then fill the system with water. I swore I would get it done this past summer.

Suddenly I realized it was October and getting colder and my shop was getting a bit cool during the night so first thing in the morning I was wearing a jacket. I kicked myself in the behind and a week ago took the time to get things put up. It took all of about 90 minutes to install the thermostats. Then last Friday I started filling the system with water. I have a single zone, with four loops of tubing, and it took me about 3 hours to get it all filled using just at 14 gallons of water. I used distilled though not sure I needed to. I did not put in any antifreeze as I don't intend on letting the place freeze. I may change that at some point, but for now it is just clean H2O.

I fired up the water heater on Saturday afternoon and thought it would take 4-5 days to get the floor warmed up. I went out on Sunday morning to check it and wonderfully the place was a nice 68 degrees or so. I had to turn down the thermostat because it was actually too warm. I fought the cold all last winter, making trips to the propane depot half a dozen times with 4 - 6 bottles, endured the smell of the burned propane, all because I didn't take the 5 hours to get the system finished. I ask myself at times, How dumb are you to not just get it done?

I can now say that it is incredible to have radiant heating up and running. Had to have the overhead door open for about 90 minutes loading some cabinets into a trailer and when I closed the door, the shop still felt nice and warm.

If anyone ever is considering radiant heat, don't think, just do it.

[Bruce Page]

I would love to have radiant heating. I used kerosene heat for years in my garage shop before installing an overhead hotdog type heater. I wish I would have installed it years earlier.

[Ken Fitzgerald]

Mark, I am envious! I wanted what you have but the city code required I have a water source in the building or a special protection circuit in case of a leak which the only quote I got was beyond my means. Thus I have a Lennox hanging space heater which works well but I'm sure not as efficient or economical as the radiant floor heat!

[Lisa Starr]

For Ken and others considering radiant floor heat without a source of makeup water. You only have to install a low water cutoff to meet code in most jurisdictions. My particular boiler recommends one even when connected to a water supply. They cost from $200 to $600 depending on the design. The idea is that if the system is low on water, the cutoff prevents the system from firing.

[Frank Pratt]

Radiant heat is nice, but not optimal for my situation where I keep the shop (garage) at about 5 degrees when not using it. When I work out there, I want to heat it up in a hurry. My shop is heated with a 60,000 BTU residential forced air furnace with ducts ran to the floor level at the far corners on either side of the OH door. This brings the shop up to a comfortable working temperature in a short time and it's very even heat floor to ceiling. But it wasn't cheap having all that installed.

[Jim Becker]

I don't have radiant, but I'm "more than pleased" that I invested in HVAC for my shop for four season comfort. I don't make it "cold" in the summer and "hot" in the winter...it's just plain comfortable to spend a lot of time out there now. Of course, being fully insulated now also factors in. I went mini-split for my installation and it barely blips our energy bill, unlike the resistance heat I used to use.

[Jack Frederick]

Most of the gas fired wall hung boilers have an electronic low water cut-off built in. When I built my 30x34 shop I considered radiant. I have been in the business most of my life and can buy wholesale, get the boiler for free and install it all myself. I chose not to do it for cost reasons, but most importantly the way I use the shop. My use is intermittent. Therefore, it was best, for me, to go with the Rinnai DV wall furnace. Radiant is great if you are maintaining temp all the time. It doesn't really do will with set-backs. Radiant is wonderful heat but I'm happy that I did not do it in the shop.

[Kris Cook]

Am envious especially this morning as it is 10 degrees outside. I have a 1,500 watt heater going in the uninsulated shop/garage to try and keep some of the chill off. It was 28 degrees in there this morning, so doing a little good. I am going through the propane thing right now and am sitting here messing around on the computer waiting for the shop to warm up. Radiant heat sounds nice although wouldn't have worked for me. Planning to get the wood stove going this week so I can work out there when I have time.

Enjoy your warm shop.

[Mark Blatter]

Am envious especially this morning as it is 10 degrees outside. I have a 1,500 watt heater going in the uninsulated shop/garage to try and keep some of the chill off. It was 28 degrees in there this morning, so doing a little good. I am going through the propane thing right now and am sitting here messing around on the computer waiting for the shop to warm up. Radiant heat sounds nice although wouldn't have worked for me. Planning to get the wood stove going this week so I can work out there when I have time.

Enjoy your warm shop.

Hey Kris - I know what you mean. I lived in Helena for many years and had a big unattached garage that wasn't heated. My father pulled a pellet fireplace out of his house and gave it to me. I installed that in my garage and it was so nice, but I ran through bags and bags of pellets. There is nothing like a cool fall day in Montana.

[Kris Cook]

There is nothing like a cool fall day in Montana.

Ha.

Seems more like January right now.

Supposed to be back up in the 40's by the end of the week.

[Bill Carey]

I have a mini split system as well in the second floor office over my shop. During the summer I keep the door open with a box fan blowing cold air downstairs and it keeps the shop nice and cool. I have an electric ceiling mounted heater in the shop that is VERY expensive to run, so I'm in the process of installing some duct work and a used blower to take the hot air off the ceiling of the office and blow it down to the shop floor. Hopefully that'll help some in keeping the elec bill down. It'll cause the split system to run more but it is much cheaper than the ceiling mounted unit to run.

[Kris Cook]

Bill - I also have a second floor office above my shop (still trying to get completed). If you had it do do again would you have sized your system to allow a second air-handler from the mini split in the shop downstairs? That is what I am planning to do and am curious what your thoughts are.

I will also have a wood stove in the shop below the office.

[Bill Carey]

Hey Kris - when we bought the house the shop/office was done, so I didn't get a choice. But were I doing the work now, I think I would go with a high efficiency HVAC system. The nature of the work means there is very little duct work, and natural gas is the best option here. And it would save a 220 circuit for the shop - always nice to have. Wood stoves I have no experience with but they make me nervous. Wood shop and fire are not words that should be in the same sentence. :eek: IMHO.

[Thomas Eustis]

I am just finishing up a stick built 28x40 shop with 10’ ceilings (should have the CO in a few days). I kind of went all out with 7” concrete floors, in-floor radiant heating powered off of a super efficient natural gas on-demand hot water heater (Takagi), bathroom, a small office, and an 8/12 pitch so the attic is huge. Also added 10 8’ LED fixtures (88k lumens) and a 8x12 R19 garage door, and finished it with board and batten. Looks awesome. BTW, I went WAY over budget...

I still have not cranked up the floor heat (waiting on CO) but if you are pouring a slab it makes sense to get the tubing in the slab. You’re only going to pour the slab once. For my shop the 1000’ of 7/8” tubing was only about $1k. I used a system designed by The Radiant Floor Company in Vermont.

418512

[Lisa Starr]

Thomas - go easy when you turn the heat on in the new shop. If you warm the concrete up too quickly, it is much more likely to crack. Also, depending on how it is set-up, consider lowering the supply water temperature while you are first warming it up.

[Frank Pratt]

Why the 7" floor.

[Thomas Eustis]

go easy when you turn the heat on in the new shop

I had not considered that. Good idea. Thanks.

[Jack Frederick]

Should you choose to go forward with the radiant do install a floor sensor. Go to the Rehau and Uponor sites for some good info.I always keep some pressure in the tubing for the pour and add a few drops of oil of wintergreen or peppermint to the tubing. That way if some meathead on the pour gets a bit to aggressive with the pour and cuts the tubing, you know it and can do the repair...hastily. It happens. also, use the Pex-A tubing. it has the oxygen barrier and is better.
Tankless water heaters are generally designed to provide domestic temperatures. You will have widely variable flow in a home and a large delta T. Boilers generally will have a relatively fixed flow and a small delta T. Most manuf do not allow their tankless in heating applications. Takagi does allow this application and there are a lot of them out there working successfully. I would suggest that you go the extra mile and get a true wall hung boiler. There are many out there today. Navien, Lochinvar, Weil-McLein, Rinnai. They come in combi's and heat only. I am a fan of the new Rinnai Model I. You get a SS HX, modulating pump and a very robust outdoor reset (ODR) program built in. They are designed for what you are doing with them rather than putting a square peg in a round hole. The ODR will maximize your comfort, efficiency and overall performance of the system. You will be in to a radiant system for quite a pretty penny. Don't scrimp on the engine. Also, make sure your slab edge insulation is in order. I got a call from a contractor to go look at a customers home last year. Probably a 1500 sq ft very beautiful home. It was radiant heated and had zero slab edge insulation. In our relatively mild climate here in the foothills it was costing her $800-1000/mo for heat. She abandoned the system. She now heats the whole place with the EX-38 i suggested. Radiant is wonderful heat, but it is neither inexpensive to install nor to operate. You can minimize the operation expense by meticulous attention to the insulation package.

[Mike Kees]

I installed pex tubing and insulated under my entire floor slab on my shop. My perimeter foundation is a four foot frost wall of Superform ICF. Budget ran out before I got to the boiler . I heat my entire shop with two overhead radiant gas fired tube heaters one is 50000 btu and one is 70000 btu. The floor is always warm,the insulation under it is the key as well as the frost wall around it that stops frost from penetrating under my floor. I probably will never hook up the floor heat now. In my mind money spent on insulation is money not wasted. I have r-28 in my walls and R-60 in my roof. Keeps me cool in summer and warm in winter.

[Edward Dyas]

ON days I don't plan on spraying paint I heat my shop with a wood stove. Good way to get rid of scraps too.

[Mike Kees]

I really wanted a wood stove in my shop as well,but insurance company vetoed that idea. If I ever hook up my in floor radiant heat I will probably use an outdoor wood furnace and circulation pump to power it.

[Eric Danstrom]

...I went mini-split for my installation and it barely blips our energy bill, unlike the resistance heat I used to use.
I had to go to the google on this. I didn't realize how a heat pump could heat at 1/3 the cost of resistive heat since resistive heat is 100% efficient. Before I can run a mini-split its $3k to upgrade my service from 100A to 200A. But then I could run a welder and 220vac power tools.

Edit: Lol, now I understand why they sell window size heat pumps that run on 120vac. $500 for a window sized HP that will handle my single car garage and hooks to my wifi makes total sense. Hmmmm.....

[Jim Becker]

Eric, as long as you live in a climate that's within the sweet spot for a heat pump type system, today's units are pretty darn efficient, especially the mini-split type which can exceed 20 SEER. The temperature range should be in the specifications for every unit. Mine is supposed to be able to work down to -5ºF, but thankfully, that would be a very rare thing here in SE PA. They are certainly not inexpensive to acquire, of course, but they really work well. The small window type heat pumps work in a similar way, so if their output is capable of serving your space...and you have a window or can make a "window" in your wall...it's worthy of consideration.

[Bill Dufour]

I have never seen a noise rating for a window unit and they are less efficient then a minisplit. Note that db noise rating is a log scale so about 7-8 points more is twice as loud to the human ear. Many units are twice as loud or more then my Freidrich units. Some are louder on low then my units at forth speed!
Bil lD

[Ronald Blue]

If the floor was set up properly on install radiant heat should never be anymore expensive than any other form of heat. Other than burning wood you harvest yourself. Why would it be better to use a much more expensive hot water boiler than an on demand gas fired water heater. I got my specs from the Radiantec out of Vermont. They make their living on radiant heat. They said using on demand hot water heaters is the best heat source. Hot water boilers aren't designed or intended to run in the 120 degree range which is the ideal temperature. I hope to have mine going in the next month. So I will be able to give a first hand report. Usually when the result isn't as good as hoped for it's because the insulation isn't adequate. Some people were given poor advice upfront. They used the radiant barrier attic bubble insulation under the slab. That's woefully inadequate. I have 2" thick high density Styrofoam under my slab. It's amazing stuff. You don't even leave a foot print when you walk on it. Like with almost everything you do if you don't do the prep work needed the outcome won't be satisfactory. I know several people with it in my area and it's the best heat ever for a shop. When the floor is warm you don't need the room temp to be 70. You can set the thermostat at 60 and it's cozy. I will update my own experiences hopefully by the first of the year.

[Bill Dufour]

I think radiant heat is not for my climate. Mostly I need a little heat in the morning and evening nothing in the mid day portions. Does anyone use it for cooling?
Bil lD

[Jeff Bartley]

I think radiant heat is not for my climate. Mostly I need a little heat in the morning and evening nothing in the mid day portions. Does anyone use it for cooling?
Bil lD

The only downside to radiant is the fact that it can't cool. I installed a system from The Blue Ridge company out of Washington. My shop is a little over 1000 square feet and it was a little over 3k for all the pex and the complete system. By 'complete system' I mean that they build and mount the system on a stainless sheet and ship it complete. All you need to do is hang it, connect all pex and electricals, bleed the system, and you're heating.

They were fantastic to work with.

Also, at least for my system, there's an outdoor sensor that tells to system to not run if the outdoor temp spikes mid-day.

I also used 2" foam under my slab and ICF forms for my foundation walls.

[Jim Becker]

I think radiant heat is not for my climate. Mostly I need a little heat in the morning and evening nothing in the mid day portions. Does anyone use it for cooling?
Bil lD

Bill, what you state is pretty important. Radiant heat can be a wonderful thing as it's comfortable heat. It's singular downside is that because you are heating a large mass of solid material which in turn heats the space, it's a technology that you want to be able to turn on at a particular point in time during the year...and leave on until heat is no longer required. it's not good for climates that are extremely variable or those that have short/sporadic needs for heat. The reason is that it takes some time to heat the mass up to a stable temperature and starts/stops just are not very efficient. Toward your question, I don't believe it would be effective at all for cooling in the traditional sense. Honestly, for your climate (and even mine) a heat pump/MiniSplit is a better overall solution, IMHO, because of the efficiency and amenability to only using it when it's needed.

[Tom M King]

I like to work with hand tools in front of a fireplace in really cold weather.

[Mark Blatter]

My son asked if there was a way to put a meter on my gas line since I just came straight off the house, but after the meter. I know there are meters I can buy, but I am wondering if there is a way to estimate my gas usage based on water produced. I have a direct vent to the outside so obviously some water is lost there as vapor, but I still collect the actual water that drains out into a bucket until I get a drain line installed.

Any thoughts?

I read that every pound of natural gas produces 2.25 lbs of water, and that the water is approximately 12% of the total weight of gas burned. I also found that a pound (as with most of this these are averages and could be very different depending on location) of ng has about 20,000 BTUs.

If I produce 5 gallons of water a week, converted to NG is 42 lbs, or 833,333 BTUs, and since we are charged $10 per mcf, it would be about $36 per month to heat.

Does this seem anywhere near correct? Lots of variables I know and my number could be off by 40 - 50%, but is the actual calculation right?

[Bill Dufour]

I think the efficiency of water condensation. will vary a lot depending. on outside air temperature and humidity. Burning. equal quantities of gas will produce a lot more condensate on a cold humid day then on a warm dry day. Any wind will also reduce the condensation that stays in the catch bucket.
I bet these effects could cause a 100% difference in condensation caught.
Do not know i it still works this way but San Francisco used to charge for municipal steam consumption by measuring condensate from each building.
Bil lD

[William Hodge]

I am about to hook up a new heat source for my radiant heat. I used to heat the water with propane.

I have solar panels, and a $1,400. credit on my electric bill. I make about 50% more electricity than I use in the house and shop.

My plan is to buy a 40 gallon water heater, and circulate the water through it at the lowest setting, with no controls. The total cost of set up would be $450., including the water heater and wiring. I have a circulator pump. The radiant heat would supply the base load heat. The electric radiators and gas hot air furnace would fine tune the temperature. my goal is to get the floor to 60 degrees, and heat up all the cast iron.

What would be the advantage in using an on demand heater? Given that I want the system to be slow to heat up and cool down,it would seem that a water heater would be adequate. I have also had trouble with the computers failing in on demand heaters. I love computers, but in a base load heating system, they seem unnecessary. The waste heat from the tank will just be another source of radiant heat.

[Jaromir Svoboda]

I'm using on demand water heater to heat my 1,440 sf shop without any problems all winter. It will run for 2 minutes every 20 minutes or so to keep it at 59F.

[Jack Frederick]

Trouble with the pub's on the water heaters? William, I don't know all of the manuf of gas on-demand but do know the major brands very well. The pcb on them are very robust. The exception on all of them would be seeing "strange" voltage. They need a good sine wave inverter to operate reliably.

[Jim Becker]

I learned a hard lesson with our tankless water heating systems here and both now have good surge protection on them. Replacing the PCB was going to cost north of $500 and a new unit was $900. I opted for the latter in this case because it was less complicated and the fried unit was out of warranty anyway.

[sean meltvedt]

I think radiant heat is not for my climate. Mostly I need a little heat in the morning and evening nothing in the mid day portions. Does anyone use it for cooling?
Bil lD

Bill it can do limited cooling. It is very climate dependent. I use it to heat and cool my home and shop. Summers can be mid 80’s with 20+hours of sun. But fortunately when it is hot, it is also dry. If the humidity is up, you can only cool the slab down to just above dewpoint-otherwise you will have wet floors and anything touching them such as wood or rugs can and will mold. So if you have the climate to go this route, make sure you control the slab temperature above dewpoint for the interior humidity.
Cheers
Sean

[John C Bush]

It's good to have a good friend in the plumbing business. I use a standard NG 60 gal. water heater, circ pump, simple(cheap) thermostat, relay, and a manifold for the
4 zones of 250' length of pex. I usually keep the temp~60 deg as the PNW climate is mild in the winter and summers don't require AC. Very simple install and works
perfectly. Not sure of energy efficiency but I do turn it down to < 50 deg if not using the shop much. An on demand(tankless) system isn't needed and the slab holds the temp
really well. No forced air to blow dust around as well.