Heating a small room

saikosis

I've got a house from the 1800s. The house has one-pipe steam. We've got a barn with no heat. Connecting the house and the barn is a little, one-story saltbox kind of structure that was probably once a wood shed. It got a crawl space underneath that is open to the outside. Previous owners put an electric baseboard in there.

The saltbox style made the storage area in the room kind of useless. 1800s construction and the open-to-the-outside crawlspace made it really cold in the winter. It has doors to the house, barn, and backyard but no door to the driveway. Because of all that, it's kind of a useless room. Well, to be fair, in the winter, it does double as a giant walk-in fridge.

We're currently renovating that space and turning it into a mudroom. We gutted it and ripped the roof off. We were suprised to find that a previous owner had actually insulated the lower walls. However, the upper walls, ceiling, and floor were not insulated at all. I have no idea why someone would bother insulting but then do so little.

The saltbox shape is gone and the roofline is now symmetric. Inside, the ceiling will be vaulted. A door to the driveway was added. The crawlspace is staying, unfortunately, but we'll close it off as best we can. The crawlspace skirt, floor, walls, and ceiling will get closed-cell foam. The room is about 12x15. The back part will be a closet. The only question left is how to heat the thing.

The room is pretty far from our boiler. We could maybe run steam to it, but it'd be a challenge. The contractor doing the work recommended either an electric heated floor or an electric in-wall heater with a blower. They said the in-wall heater will beat the electric baseboard radiator because it's got a fan to circulate the warm air. They said the heated floor will beat both because you get thermal mass from the floor. The floor will be glazed porcelain tile. He proposed an 8x10 mat (smaller than the room), because the heat will spread through the tile.

I think the in-wall blower is like $300 and the heated floor is like $1300. I don't want to spend all this money on the renovation and still end up with a cold room. I'm also worried about electric costs. We pay $0.31/kWh for electricity, down from a high of $0.50/kWh this past winter.

Any suggestions?

saikosis

P.S. I have a Weil-McLain PEG50 with an indirect water heater. Presumably, you could do a wet radiant floor from the boiler, but distance from the boiler might still be an issue.

Jamie Hall

A few thoughts. First, in general mud rooms weren't -- and aren't -- heated. But that has to do with what they are for -- a place to put your muddy boots and whatever without tracking the mud into the house. And you don't want them heated because they are on farms, and warm farm mud has... shall we say a presence to it?

So it's not going to be a mud room, except as a manner of speaking. A heated entry way, perhaps.

OK. Having said that. First, unless you can really seal off the crawl space, I'd avoid a radiant floor. Unless it is unbelievably well insulated, you'll lose most of your heat outside. The simplest solution is that fan assisted electric wall heater. If you don't insist on bringing it up to house temperature -- keep it at, say 40 or so -- it may not be all that great a hit on your electric bill. You might also consider overhead electric radiant heaters such as are, in fact, used on farms where spot heating is wanted. They don't heat the space -- that's not the idea -- but they do warm the occupants of the space. They could even be hooked up to an occupancy sensor so they only were on when someone was using the space. That -- and keeping the temperature low -- both assume that this is more of an entry space than a living space.

You don't mention your fuel source for the boiler, but if it is LP you could also use a small -- say 30K BTUh -- vented gas wall heater. They are very effective and at your electric rates likely to be a lot cheaper to run.

jesmed1

I second the gas heater option. It will cost you more up front, but it will heat the space very economically, and in the long run be cheaper because gas heat is so much less costly than electric resistance heat. We had an unheated sun porch that we enclosed and installed a 10,000 BTU/hr Jotul freestanding stove/heater that I found for a few hundred bucks used on Craigslist in excellent condition. The main cost was running the gas line to the porch. You can opt for a basic gas heater with no ambiance, or you can cheer the room up a little with that style of freestanding stove/heater if you can spare the floor space. Either way, sized correctly, you'll be guaranteed not to go cold, and some of these have adjustable flames that you can turn up or down easily.

If you do go that route, be sure to get a vented one with the exhaust pipe going out the wall. There are "ventless" units that vent the exhaust into the room, and IMO that is not a good thing.

EBEBRATT-Ed

1.Gas fired vented wall heater would be my first choice if you have natural gas or propane.

electric baseboard will do a better job than a fan powered electric heater or

a hot water zone off your steam boiler will work but that would be a more expensive option

12 x 15 is a decent sized room but probably not worth going the hot water baseboard and I would not go radiant electric unless your convinced you're going to heat it all the time.

If you do not have gas I would go electric baseboard. If it is well insulated with good windows it wouldn't be that bad from an energy standpoint.

hot_rod

In a mud room a small fan device is nice for quick drying of wet clothes
Radiant walls are nice and and easy to retrofit. Same with radiant ceilings

saikosis

Pinterest calls it a mudroom. Let's call it an entryway. We want it above 40 F. Ideally, it should feel like any other room. Is it too much to hope for it to be above 60 F? If it helps, the adjoining room has the biggest radiator in the house at 61.33 square feet of EDR.

My barn hasn't housed animals in a long time (unless you count mice), so there won't be a lot of "presence" to what we track in.

The floor will get 5" of closed-cell foam. R-32, I believe.

I hadn't considered something gas fired. We have natural gas. I don't think we have the space for what I'm seeing on Jotul's website. The in-wall electric heater that they proposed would fit between the studs. Any suggestions for a gas unit that would fit similarly?

I'm surprised that an electric baseboard would be better than an in-wall unit with a blower. I assumed it'd be better to circulate the warm air.

Jamie Hall

Any number of gas wall heaters and furnaces for recessed mounting. Williamson makes a nice line of them.

EBEBRATT-Ed

Williams, Rinnai, Empire all make gas fired heater some are surface mount some recessed. Do NOT buy any that do not vent to the outside, ventless heater are not safe in my opinion.

This is the best way for you to go. Nothing to freeze you can run it or turn it off. Good choice for a mud room.

Installation is simple the heater gets mounted and vents out the back (they have to be on an outside wall). 120volt electric power (they use very little power) a 24 volt thermostat to operate it and your gas line.

They are sold in many sizes to use in those applications

hot_rod

Anything with a fan will bring the room back to temperature quickly as the doors open and lose heat. If that is important.Gas fired may be less $$ to operate.

saikosis

After talking with plumbers about gas heaters or an under floor hot water loop, I decided to go with the electric floor.

The electrician is already here for the rest of the wiring in that room, and there was already power for the old baseboard heater, so the incremental cost of labor for doing electric heat is very small. He has everything he needs, right where he needs it. We're basically just paying for the unit itself.

There's no plumbing work in that room, so we don't get any of the plumber's time for "free" like we do with the electrician. Plumber's charge a ton of money here, so the total install cost would end up being way higher. Nothing is where it needs to be, and getting it there is complicated because of the age of the house, etc. The in-wall furnace is about the same price as underfloor electric heat, but labor would add thousands of dollars.

The in-wall electric blower would be cheapest at $300 and it would respond the quickest. However, it's basically forced hot air, which I don't like.

The electric floor is $1300. It's going to respond slowly, so we can't exactly turn it on/off right just when we want it. I don't have time-of-use electric metering here, so I also can't save money by charging the floor at night. I might lose heat through the floor, although I'm hoping the spray foam helps. However, it's nice on the toes, and there's some value in that.

The in-wall gas furnace has a similar unit price as the electric floor with similar benefits as the electric blower. It's also forced hot air though, and it's significantly bigger than the electric blower, so you'd know it was there. Also, looking at clearances, I'm not even sure we'd be able to to put one in. The smallest units I could find would be overkill for the size of the room, although maybe you could downfire them. Getting a gas line to the space might have been a problem too.

If I had good access, a hot water loop in the floor would probably be ideal. I could tap into the boiler that's already hot all winter long and I'd get warm toes. Also, I'd have my choice of fuel at the boiler rather than doubling down on gas just to heat this one space. However, I don't have good access.

Here's what I figured for running costs of the electric floor:

1 kW heater in the floor * 12 hours per day * 120 days per year * $0.50 per kWh = $720 per year

With those numbers, it'd take several years to break even on the higher installation costs of a gas system, and that's without factoring in the price of gas. Given the tradeoffs and unknowns, I felt like the electric floor was the best option.

Thanks for the advice.

EBEBRATT-Ed

Electric radiant is fine if the room will be used when it is needed. With no plumbing in their to freeze you could shut down the heat when the room isn't used. That is why I wouldn't choose radiant. To slow to respond if you shut the heat down. But only you can decide what the room will be used for. For me it would be electric baseboard. No fan so it is not like hot air. You can put enough in so it will respond quickly and shut it down when you don't need it. JMHO

Lance

I look at this room as too small to worry about. The heat loss factor is small?? 500watts of lighting might heat the room. Or infra-red lights to heat the bodies. But the goal to keep above freezing is small. If the goal is to keep the room at (insert temp here) than best advice could be given. However, based on the expected load and knowing how a mud room is used, even 55F is good. Life of and service saved will be well worth the electricity used considering the cost of other methods. Simple here to install and simple to replace is my motto. Electric baseboard is the key. Quiet, no fans, and economical considering the low loads. Suspected no fail, no service life over 30 years or more. Night setback would be a great option. Unused, the space can be kept at lower temps. If shorter recovery is desired, add two small units on two separate stats. Easily simple on / off stat. Either one could easily be a lead lag control just based on the set points of each. I would make it 220v and probably only need a 20amp circuit. Beauty of this is only 50% can fail at a time. Better yet, make both on separate fuses. What will the load be? 1000 BTUH on the coldest day or what? Makes no sense to engineer until load and designs are established.

ricka1234

gas vented heater or even a pellet stove...
way bettr options than electric. 

mvickers

30+yrs ago, during the construction, in our 20x30, mostly in-ground block basement, with 12x12, draped plastic wall space for a sleeping area, I used a 220V fanned heater to keep it sleepable. Worked great, still have the heater, and about to use it similarly again

ronaldsauve

I would go minisplit. I think your using the closed cell foam is a very good idea, especially with it being over a crawl space.

saikosis

I assume the renewed interested here is due to the shoutout in the weekly email. I appreciate the suggestions, but I'm sorry to say that the ship has sailed though.

There's not enough room for a pellet stove. Anything involving a plumber would be much more expensive. Payoff would be many years, possibly as much as 10 or 15.

I considered a mini-split. If the room was more open to the rest of the house, I think it would have made a lot of sense. We could have benefited from spillover effects of the heating and cooling. There's only a small doorway to the rest of the house though, so I was concerned we wouldn't benefit from the full effects of the mini-split. I could be thinking about it wrong. The cost is high too.

We don't have AC in the rest of the house, so it's likely we'll do mini-splits sometime in the near future to ward off the hotter and more humid summers that we've been having. If we go that route for the rest of the house, adding a small unit in this room might make sense at that time. We'd be adding an incremental cost to a bigger project (just like we're doing now with the electric floor), so the financials would work out better.

If the electric floor doesn't work out (can't keep up with the cold, too expensive to run, whatever), I'm out a bit of money but not a ton. If we do mini-splits eventually, having the ability to heat the floor might still be nice as a separate option.

Kirk Shriver

If it's not too late I would suggest that you sandwich "bubble-foil" between the floor joists and the underlayment. It won't add much to your overall cost and it serves to best match a radiant heat source as it has a very low R value but R values are not quite the same when dealing with radiant heat. Remember the sun is our only source of natural heat on this planet and it provides that heat after traveling 93M miles through cold empty space. I have a small off grid cabin and before I built it I watched way too many YouTube videos about cabins. I never forgot this one https://www.youtube.com/watch?v=xPTJD9nuWvQ. Good luck, I think your radiant floor is more than good enough and it will make your toes toasty and happy.