Hybrid biomass system

[L P]

I've been long mulling over how best to heat the house when it's finished, it should be pretty thermally efficient. I'm not interested in RHI as have acquired a sh eta pek90 without rhi and have an old passat log boiler I never hooked up sitting in the barn, along with the existing grant oil boiler which has served me well. For ultimate flexibility I'm thinking to link the passat and eta into a big buffer tank, so use the passat for all the free wood on the farm, let the eta take over when time doesn't allow to stoke the log boiler and plumb the Grant in for summertime hot water and third redundancy. Passat and eta are oversize for the house so considering a thermostatic valve opening and heating the workshop on any excess peak warmth.... thoughts?!

 

[Wisconsonian]

Seems a little over complicated, but I'm going to make it worse. If this is a new house, why not a heat pump for most of the spring and fall? And the pek 90 for the coldest weather? take the time to cut, split and dry the wood, or burn it in a bonfire if it's not worth the trouble, let the log boiler sit in a place ready to hook up in an emergency, or sell it.

 

[L P]

Seems a little over complicated, but I'm going to make it worse. If this is a new house, why not a heat pump for most of the spring and fall? And the pek 90 for the coldest weather? take the time to cut, split and dry the wood, or burn it in a bonfire if it's not worth the trouble, let the log boiler sit in a place ready to hook up in an emergency, or sell it.

I don't believe in heat pumps, all I hear is they are as dear in electricity as an oil boiler in oil. The most efficient for me is the log boiler, it's a big thing, no splitting needed, it will take rings or 4' long cord wood so not much processing. Only reason for putting the oil boiler in the mix is that the pec 90/log boiler would be more efficient via buffer tank, but oil would possibly be more efficient for direct heat in the summer months, bypassing the buffer.

 

[Wisconsonian]

Even without the buffer tank, the pek90 will be way more efficient than the big log boiler. You'll want something for hot water besides burning wood, but that could be electric also. A tempering tank, and then a heat pump water heater makes a lot of sense, but maybe not right now? Your electric rates are all over the board, and the tech may improve, of course oil prices could go to the moon also.

The reason I suggest a heat pump for spring and fall, is they will be much more efficient then, and your heat load will be much less than in the coldest weather. Sounds like a new, or remodeled house, so it could be so efficient that the hassle of burning wood is not worth it outside of the cold spells. Mini split air source could work great, knowing nothing about the existing heating system, size etc.