Heating duplex without ductwork.

15 Replies

I own a duplex which currently has electric baseboard heat that was installed by the previous owner. It is an older house and electric heat is really high (no off peak as it is the only source). I live in northern Minnesota... regularly 20-30 below zero.

The house used to be heated with a natural gas hydronic boiler, the former owner was an electrician and I am thinking the boiler malfunctioned and instead of replacing it he installed electric baseboard heat instead.

The pipes for the radiant heat are not hooked up in some areas. I had a plumber look at it and he recommended not to hook up the radiant heat again due to cost of fixing what is there.

both of my units are two bed two bath. I am adding two more bedrooms and one bath in the basement which will be connected to the unit on the main floor. I am planning on putting in duct work for a natural gas unit to heat the main floor and the new basement remodel (which will all be one apartment).

My question is what should I do with the upstairs apartment? I cannot feed the duct work to the upstairs apartment because I have no way to split the utility bill between the two units even if it were zoned. I had a natural gas line fed up to the upstairs unit because I was initially going to put in a wall furnace in to act as a large space heater. The unit is approximately 800 square ft with an open floor plan so I think that a central unit would work fine. However, the wall furnaces that I have been looking at are only rated at around 75% efficient compared to the regular central air units that are around 95.5% efficient.

Any suggestions on heating a 800 square ft apartment without duct work using natural gas efficiently? Maybe a mobile home furnace?

Sounds like radiators would be the thing for the upstairs unit. I believe the piping for that can even be PEX, so that could be easy to plumb. Gas lines can also be flex in many jurisdictions. The challenge is where to locate a boiler for that unit.

there are old radiators there. Are you saying to cut the loop from the down stairs and close it to isolate it to the upstairs unit? Would a domestic ng water heater be sufficient to heat that small of an area? Standard hydronic boilers would be too big.

I would leave the electric heat, it is after all (I assume) separate and paid by each tenant. Could you then maybe install a cheaper or even used ventless natural gas fireplace in each unit? A fireplace adds instant charm & perceived value and you can tout that as an energy saver.

I understand you want to move away from the electric heating and change back to natural gas. I have no tips for you on that.

However if you decide to stay electric (and ductless), there are better choices than baseboard heaters. Our new favorite is a new Cadet wall heater called the Energy Plus. Retails for about $200 and is worth it IMO. See http://cadetheat.com/products/wall-heaters/energy-plus. Tenants like it and we haven't had any issues with it so far.

Originally posted by @George C. :
I would leave the electric heat, it is after all (I assume) separate and paid by each tenant. Could you then maybe install a cheaper or even used ventless natural gas fireplace in each unit? A fireplace adds instant charm & perceived value and you can tout that as an energy saver.

The electric baseboard heat was around $900 for the whole building when I purchased it. I put in new windows, insulation and numerous other things which dropped me down to around $750 per month for the whole building this last winter where we had a high temp of 20 below zero for about 2 months. I am currently covering the cost of heat and increased the overall rent per month because I am afraid that in the wintertime my tenants will not plan on a electric bill for $375 per month and will then not pay their rent.

A ductless mini-split heat pump will not work here because they are only efficient at around 5 degrees above zero and use the same system as an electric baseboard heater when the temp outside is so low, so it will not save me any money.

Once I can get the cost of heat under control with natural gas I will lower the monthly rent and make the tenants responsible for all utilities. My duplex is close to the local college and with the demographics in my town this is the target market. So keep in mind that I am most likely working with college students.

Since you describe the upstairs apartment as open plan I wonder if it might work to put in a small gas furnace and do exposed ducts -- just go for a more loft/industrial look. It's quite the fashion around here, you see it in a lot of upscale apartments and condos. Not having seen your space I don't know if it's practical, but it's a thought

@Aaron Carter typically a ng water heater does not heat the water hot enough to serve as a heat source for hot water baseboard heat. There are boiler units that are high efficiency that are about the same size as a hot water heater. You really don't need a huge one for 800 sqft. You need to do some more searching for contractors that specialize in hot water heat. Have them look at it not a plumber. Heating and plumbing are not the same trade and you need someone that eats and breathes heating.

Ask other landlords around town to see who they use for hot water heating. You will probably need to ask 4-5 guys that know heating to look at it for suggestions. Some will also have way out there ideas as well so you need to learn and select the one that knows what they are doing.

Originally posted by @Bill S. :
@Aaron Carter typically a ng water heater does not heat the water hot enough to serve as a heat source for hot water baseboard heat. There are boiler units that are high efficiency that are about the same size as a hot water heater. You really don't need a huge one for 800 sqft. You need to do some more searching for contractors that specialize in hot water heat. Have them look at it not a plumber. Heating and plumbing are not the same trade and you need someone that eats and breathes heating.

Ask other landlords around town to see who they use for hot water heating. You will probably need to ask 4-5 guys that know heating to look at it for suggestions. Some will also have way out there ideas as well so you need to learn and select the one that knows what they are doing.

Thanks Bill, I agree with you that I need to find someone who knows` what they are doing. I have had a couple come in and have not been impressed with their knowledge base. I live in a rural area about 13000 people and there are only a few heating companies but I will make a few more phone calls. Thanks.

If you have room in the attic you could furnace and ducting into that space with duct openings in ceiling. Not the most energy efficient but should be better than all electric. Have done this successfully to a 3 bedroom upper in Wisconsin.

If you want to invest in doing it right, there are tankless "on demand" combination hydronic and domestic water heaters. But you do need to find that heating specialist. I've been disappointed with even some of them, stuck in old fashioned ways who won't do radiant or even use math to calculate how large a boiler needs to be.

This guy's here in the Twin Cities, but might be a good resource for you. He has a lot of information on his website. I don't know him, but his approach uses math and seems interesting: http://www.badgerradiantdesigns.com/

I thought I would post my progress. I had a REAL heating guy come out and take a look around. He recommended a central air furnace placed next to where the main gas line comes in, which would facilitate another meter to separate the gas bill between the two units. The central air would feed the lower unit which is two levels.

For the upper unit we can use the gas line that was already ran and put in a 80% efficiency gas wall furnace. Because of the open floor plan of the 900 square foot apartment he said that even though the efficiency is lower than a regular central air unit, around 93%, the cost savings over time would not be enough to justify the cost on installing another high efficiency unit.

He gave me a VERY reasonable quote, so I am looking forward to getting this off my to-do list.

Great news. Amazing the difference some knowledge makes.

Originally posted by @Bill S. :
Great news. Amazing the difference some knowledge makes.

Yeah it is, I am slowly learning that I can not do or figure out everything myself just to save a few dollars. I know the people on bigger pockets reinforces that a lot. Thanks for the advice Bill!

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