Dual Fuel system in Massachusetts - oil and heat pump?

Question

Just picked up an 8000sqft building in Western mass (7 apartment, 1 commercial space) that is heated by oil and paid for by the landlord. My partner and I are looking at creating a dual fuel system, where heat pumps make hot water on the milder winter days but the oil kicks in during the bitter times. Am also having a solar contractor looking at putting up panels, with the hope that once the solar loan is paid off, we'd be getting a large amount of our heating for free (solar runs heat pumps which heats the building.)

Curious if others have experience with this in Mass where the solar incentives are solid and if so, any advice?

Sean Burns · Answer

Hello, I am a gas utility worker in Mass and have seen systems like this and this is my advice. The only issue with the solar for the power source for the heat pump is that when the heat pumps are needed the amount of sunlight is reduced, short days of winter and night time, it is essential to have a good battery back up to help with the demand. As for the change over between two heat sources you can install a temp sensor to restrict when the back up can turn on, a good low voltage electrician can figure it out for you. I would also look into converting to a propane system, I have been to a few housed where oil tanks have failed and the result is a condemned house and long repair times.

George W. · Answer

I'd just keep the oil boiler and focus on system efficiency. Do a heat loss calculation on the building and make sure the oil nozzle is the right size in gph for the needed BTUs. You'd be surprised how many oil nozzles that I see that are double the size they need to be. Next hire a pro to clean the heat exchanger and make sure your draft is good in the chimney.

the only thing I would recommend Changing system wise is if you have a hot water coil in the boiler. Buy an indirect storage tank. It has a lot more capacity and is more efficient because the boiler won't cycle Evey time someone needs hot water. Also if you don't already have a programable thermostat, change that.

Having a solar system with heat pump sounds great until the first time you have an issue with it and lose heat because a control locks you out. Also you'd probably need either a heat exchanger or heat storage tank (either ones not cheap). The first major problem you have control wise or system wise will lose any savings most likely. Also By the time you pay someone to install a system like that in small apartment building, it would take years to make your money back.

Colleen F. · Answer

@Christopher Ball  I have property in RI  but live in MA and having been looking in central MA for a while but we haven't bought in MA aside from our primary which we are getting ready for sale.

Both my house and rental units have oil.  We got hit with an oil tank replacement on one unit which wasn't pleasant.  Since my husband is an engineer who works with temperature sensors we have discussed changes but he is reluctant.  The biggest negative on this kind of thing is getting the oil burner going in a pinch. We have had several instances of restarting oil burners and it is just a PIA. We have been advised that having electric baseboard for Backup is more realistic even if you already have oil.

Christopher Ball · Answer

@Marc Guillaume how are you coming along in your progress?  How is the Greenfield/Turner's market? Is electrical power still cheap from northfield?

Christopher Ball · Answer

@Colleen F. Is there an update on your status?  I'm curious about doing this in Connecticut.  Also where in western MA did you purchase?

Colleen F. · Answer

You should be able to automate a switchover with some sort of temperature sensor which triggers shutoff. I wonder if that would be built in to heat pumps?   You do have to find an HVAC guy who thinks out of the box.  Oil burners don't like to be shut off though, they can be difficult to restart.

Yes, A ton of stuff in MA, I have never found a way to leverage them for my MA home but its there...

Tanya F. · Answer

Posting to follow, and also wondering how you're going to do the switchover in very cold weather? I know the heat pumps don't work on the coldest days, but we have to manually turn ours off and turn the backup on. It's my impression that it's bad for the heat pump to leave it on under those conditions. Is there a way to automate the switchover? I'm sure there is (unbeknownst to me), but curious what your contractors propose.

Marc Guillaume · Answer

Yes, exactly.  I spoke with an insulation/air sealing specialist and he suggested combining the three (solar and air source heat pumps plus oil backup) was the way to go - plus there are lots of loan programs in Mass (solar loans, heat loans for heat pumps, etc) to help move in this direction.  I'll update as we move along.

Colleen F. · Answer

No experience but do you have an oil fired boiler hot water system now or a forced air system? Sounds like hot water baseboard? So you want to install solar to power electric heat pumps to heat your hydronic system and have oil kick in if the electric doesn't meet demand?  Am I understanding this?    Be Curious to see how this works for you.