Propane heaters

[Jim Mackell]

Wonder what your experience is with propane wall mounted heaters used to supply water to existing hot water radiators? Specifically, does there exist any particular risk of fire caused by sawdust or fumes? It's my belief that these units use intake air from outside and thus there should be no such risk. But I'm wondering what the "real world experience" is. Let's look specifically at units installed in the last 5 or 6 years please.

Thanks in advance!

[Jim Becker]

There are two types of propane/gas heating devices; vented and unvented. Vented is preferred for both intake and exhaust for both safety reasons and to not have an excess moisture issue in the space you are heating. In fact, unvented units are not legal in some geographies at this point. Your fire hazard should be limited with these devices relative to sawdust. (clean them off regularly) Using finishing materials that have highly flammable (and dangerous to humans) fumes honestly shouldn't be done without a proper environment anyway.

[Jaromir Svoboda]

Are you talking about tankless water heater?

[Dave Carey]

Is that the only option? I just installed a mini-split. Smallish heat pump unit on the wall with lines to an small outside compressor. Mine is efficient down to 20 degrees F; there's a hyper version that's efficient to 5 degrees (wish I had that one last week!) Filters need to be blown off once periodically but no flames. Also cools but that might not be so important in Maine.

The house does have a tankless water heater which does suck air in from the outside and works like a champ.

[Jim Mackell]

The heating system in the shop where I volunteer is on the verge of dying. From what our sources tell us, we should be replacing our old, large antique oil boiler with 2 new boilers to carry the load. They have given us proposal for both propane and oil. Initial cost of propane is less, but in our area, using heating oil will be about $1,500. less annually for the same number of BTU's. Both oil and propane now can be wall mounted and direct vented and use intake air from outside. I personally like propane because it's cleaner but it's really hard to justify the ongoing extra expense. And there's a few folks who keep insisting we'll blow up because of the sawdust/gas combo.

[Ronald Blue]

On demand high efficiency water heaters are often used for floor heat. (Pipe in the concrete) Whether that is a viable option here is difficult to say. It depends on the system needs as far as flow. You can see Mike Hedricks in-floor set up in the workshop forum. When I get to that point that's how my shop will be heated. It's what many floor heat specialists recommend. Boilers run higher temperatures and aren't as efficient for floor heat. I suspect it might be the same situation except for the opposite reason with radiators. In floor heat you don't need the high temperature of a boiler. So a water heater works well. Some even use tank type water heaters but I don't know how well they work. The high efficiency tankless vent through the wall with intake and exhaust.

[Jim Becker]

Ronald, I haven't seen a tankless water heater used for radiant heat...since they are activated by water flow, can I assume that there's some form of circulation pump that can be thermostatically controlled? (I have two large tankless water heaters in our home, so I'm intimately familiar with them for their primary purpose)

[Don Jarvie]

Not to hijack the thread but what is the name of the “hyper” mini-split?

[Tom Bain]

Ronald, I haven't seen a tankless water heater used for radiant heat...since they are activated by water flow, can I assume that there's some form of circulation pump that can be thermostatically controlled? (I have two large tankless water heaters in our home, so I'm intimately familiar with them for their primary purpose)

Jim — That’s exactly how our radiant floor heat works. Rinnai tankless supplies the hot water to circulation pumps that “create” the demand based on the slab thermostat. The previous owner put the system in, so it wasn’t our decision. It works, but according to our radiant floor contractor it isn’t necessarily the ideal way to implement radiant heat.

[Jim Becker]

Yea, I can see that it might not be quite the best way. My observation is that tankless water heaters (while being the best thing since a hot spring... :) ) do like to work for a bit and are probably less happy with continual short on-off cycles.

[Peter Christensen]

The demand water heater (natural gas) we have heats water as needed for the house and for shop heat it heats a glycol solution closed loop in a separate burner that is pumped to a radiator and fan in my shop above the garage. If water is needed while the heat is on it changes over to heat the water and back after the hot water demand is over. It can instead of a radiator heat an in floor heat system.

[Ronald Blue]

Ronald, I haven't seen a tankless water heater used for radiant heat...since they are activated by water flow, can I assume that there's some form of circulation pump that can be thermostatically controlled? (I have two large tankless water heaters in our home, so I'm intimately familiar with them for their primary purpose)
Actually from my limited knowledge at this point if you google it this is a recommended heat source. As for short cycling as was mentioned I don't think that's an issue at all. The beauty of radiant floor heat is the evenness and the steady temperature that's maintained. You aren't running the hot water to a faucet and when the thermostat calls for heat it is going to run for at least a few minutes to warm the floor and air enough to go to standby mode. Those I know who have it rave by it. I hope to have mine going by next winter. New house has to get finished first. Yes a circulating pump is used.

[Tom Bain]

In our place, there is a separate tankless for the domestic hot water and one dedicated for the radiant floor since it’s a closed loop system.

[Jim Becker]

Makes sense to me...I was just saying I hadn't see it done that way. I'm a believer in the tankless setup for sure...having two of them in this house.

[Bill Dufour]

I think the extra expense and complications of a tankless heater are a waste in a heating system. I do not believe a tankless heater is any more efficient in the actual heating of the water. There advantage is that they do not have a large tank of hot water slowly cooling off.
If the waterheater is only running in the heating season a small pilot light and heat lost out of the tank simply add heat to the house. But I live in a climate where you do not heat the house all the time in winter. Most of the time no heat is needed except early morning and evening. Most people I know turn the heat off at bedtime.
Bill D

[Jim Becker]

There are no pilot lights on modern equipment, Bill...if the unit isn't actually heating water, there's near zero energy usage. Only a very tiny amount of electricity to power the circuitry that monitors water flow is used when heating is not in progress.

[Peter Christensen]

:) Bill be honest you guys don't need heat in your area. :) Air conditioning is more important to you. ;) If you open a deep freezer and hold your hand on the bottom for a while, that is our warm temperature of the day and has been for the last 3 weeks.

The OP is needing heat for his shop with existing radiators so we have drifted a little off topic.

[Bill Dufour]

There are no pilot lights on modern equipment, Bill...if the unit isn't actually heating water, there's near zero energy usage. Only a very tiny amount of electricity to power the circuitry that monitors water flow is used when heating is not in progress.

? ?
I thought tank type water heaters still used a pilot light

[Jim Becker]

? ?
I thought tank type water heaters still used a pilot light
The last one I had before going tankless years ago didn't have a pilot. It used an igniter. Those prior did have a pilot. I do not remember the brand/model at this point, unfortunately.

[Bill Dufour]

I do know that the borgs have water heaters that we can not buy in our part of the state. But they can sell them all in Nevada. To buy the aluminum/tar roof coating I will have to make a trip to Nevada this spring.
Bill D

[Jason Roehl]

? ?
I thought tank type water heaters still used a pilot light


They do. I just installed a new gas water heater this past fall with a standing pilot. The heat generated from the pilot does go up the flue, but it's negligible energy usage. My original plan was to try to have everything in place so that I could install a tankless unit before my water heater died, but I didn't make it. Next time--in 10-12 years, I guess.

Since this was an "emergency" install, I went with a unit that was a drop-in replacement--no major plumbing reworks, particularly with the flue. I did upgrade the cold and hot supply lines to flexible with ball valves. Total install time was 2.5 hours, with about half of that waiting for the old unit to drain. If it weren't on a stand, I could have muscled it out sooner.

[tom lucas]

I use a wall-mount ventless 30K BTU propane heater in my uninsulated shop (direct radiant, not water). I've been doing that for about 10 years now. Works good when augmented with a rug heater on the floor and small fan to push the heat down. I don't think there is ever an issue with sawdust combustion. However, when not in use during warm months, the heater can get enough dust to clog the jet orifice. I've had to remove and clean mine several times. I do keep mine covered with plastic during the warm season. Now if you spray combustibles, I would turn the heater off until it all clears out.