Shop Heat

[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.