mechdriver
New Member
- Joined
- Jan 5, 2022
- Messages
- 25
Hello,
I thought about asking this in small bits, but instead I'm dropping my whole story here in the hopes of guidance.
I renovated my Long Island, NY home myself over the last 10 years from its original unimproved 1950s design. Low-E windows, every wall, ceiling, floor and the attic thoroughly insulated. Basement remodeled and double insulated. Home was heated by an oil burner connected to hydronic baseboards which had 2 zones. I replaced every baseboard and re-zoned the hydronic system into 4 proper zones using a Taco zone controller with an outdoor reset control which vastly improved the efficiency of the older oil burner.
For cooling I installed 2 LG Multi Zone Mini Splits with 4 zones each. Initially I used them exclusively for cooling and as I observed their low electricity usage, I used them all year for heating and cooling. I recently upgraded them with base pan heaters so they can operate down to 0 degrees so they are my primary heating/cooling.
This has meant I have not refilled my oil tank in 2 years. I noticed recently the tank developed a leak, so I drained it and now I'm prepared to replace the boiler. I could install a gas burner and be done with it (I already have a gas water heater), but I'm curious about electric boilers that I can offset electricity usage with a battery bank and solar over time
I've looked into air to water mini splits, which are rare in the USA, but they would be expensive and mimic the efficiency profile of my mini splits at lower temperatures which can be a problem for the up to 180 degree water for hydronics. I'm keeping the hydronics running because of how much work I put into it and the minisplits don't warm the bathrooms directly.
So I've settled on either replacing the oil burner with gas and forgetting this foray into solar and batteries or diving into building out an electric system which I can improve over time (to keep upfront costs down)
I completed a Model J calculation showing a 50k BTU heat need. I have 3 choices on electric boilers:
54k BTU 16kw 4 element boiler (4x4kw)
41k BTU 12kw 4 element boiler (4x3kw)
41k BTU 12kw 2 element boiler (2x6kw)
Because the mini splits are run full time, this is really a standby heating system that I'm sizing as a primary for redundancy. It will be running all the time but likely only to maintain the heat relevant to the outside temperature (it will connect to my existing outdoor reset control) in its low mass tank. It's primary role will be to heat 2 small bathroom baseboards and occasionally bump the heat in a room which the mini split does not heat well enough during low temperatures. I could also figure out when the outdoor temp drops below a threshold where electric is more efficient and comfortable than the mini splits (they take longer to heat at lower temps). This is where it would then heat the whole house, potentially.
The electric burner will step up through its elements depending on demand, so I don't see it using the full kw rating all the time. I've done various calculations and I won't really know how much it will average over time until it is installed and running. I think it's wise to use the 54k BTU boiler with the 4kw elements so the staging is lower and it's not undersized.
My home is a split which cannot place a large solar array without making my roof an ugly patchwork of panels. I like the concept of a large battery pack which can power the electric burner and a small solar array that can help charge the batteries. I would likely need to grid charge the batteries on occasion, again depending on usage.
This brings me to the relevant questions:
Do I DIY the $2k electric boiler, connect to grid, observe usage and start building a high kw battery back that I can charge with solar/grid?
Or is this a pie in the sky project that's not worth it and buy the 8k gas boiler and forget it?
I realize a proper 48V battery back and inverter at this size quickly raises costs but I'm not in a hurry and would like to do it in stage such as:
-Boiler connected to grid and operating to understand accurate usage
-Battery pack and inverter powering boiler, grid charging battery pack
-Small solar grid connected to inverter to charge batteries and run boiler entirely
-Larger solar grid connected to inverter to charge batteries and run most of house?
I'm trying to use my flexibility that this is a backup system to develop a really nice setup without needing it to be running 24/7. I could see this growing into a grid tied system that eliminates my power bill.
Thanks for any advice.
I thought about asking this in small bits, but instead I'm dropping my whole story here in the hopes of guidance.
I renovated my Long Island, NY home myself over the last 10 years from its original unimproved 1950s design. Low-E windows, every wall, ceiling, floor and the attic thoroughly insulated. Basement remodeled and double insulated. Home was heated by an oil burner connected to hydronic baseboards which had 2 zones. I replaced every baseboard and re-zoned the hydronic system into 4 proper zones using a Taco zone controller with an outdoor reset control which vastly improved the efficiency of the older oil burner.
For cooling I installed 2 LG Multi Zone Mini Splits with 4 zones each. Initially I used them exclusively for cooling and as I observed their low electricity usage, I used them all year for heating and cooling. I recently upgraded them with base pan heaters so they can operate down to 0 degrees so they are my primary heating/cooling.
This has meant I have not refilled my oil tank in 2 years. I noticed recently the tank developed a leak, so I drained it and now I'm prepared to replace the boiler. I could install a gas burner and be done with it (I already have a gas water heater), but I'm curious about electric boilers that I can offset electricity usage with a battery bank and solar over time
I've looked into air to water mini splits, which are rare in the USA, but they would be expensive and mimic the efficiency profile of my mini splits at lower temperatures which can be a problem for the up to 180 degree water for hydronics. I'm keeping the hydronics running because of how much work I put into it and the minisplits don't warm the bathrooms directly.
So I've settled on either replacing the oil burner with gas and forgetting this foray into solar and batteries or diving into building out an electric system which I can improve over time (to keep upfront costs down)
I completed a Model J calculation showing a 50k BTU heat need. I have 3 choices on electric boilers:
54k BTU 16kw 4 element boiler (4x4kw)
41k BTU 12kw 4 element boiler (4x3kw)
41k BTU 12kw 2 element boiler (2x6kw)
Because the mini splits are run full time, this is really a standby heating system that I'm sizing as a primary for redundancy. It will be running all the time but likely only to maintain the heat relevant to the outside temperature (it will connect to my existing outdoor reset control) in its low mass tank. It's primary role will be to heat 2 small bathroom baseboards and occasionally bump the heat in a room which the mini split does not heat well enough during low temperatures. I could also figure out when the outdoor temp drops below a threshold where electric is more efficient and comfortable than the mini splits (they take longer to heat at lower temps). This is where it would then heat the whole house, potentially.
The electric burner will step up through its elements depending on demand, so I don't see it using the full kw rating all the time. I've done various calculations and I won't really know how much it will average over time until it is installed and running. I think it's wise to use the 54k BTU boiler with the 4kw elements so the staging is lower and it's not undersized.
My home is a split which cannot place a large solar array without making my roof an ugly patchwork of panels. I like the concept of a large battery pack which can power the electric burner and a small solar array that can help charge the batteries. I would likely need to grid charge the batteries on occasion, again depending on usage.
This brings me to the relevant questions:
Do I DIY the $2k electric boiler, connect to grid, observe usage and start building a high kw battery back that I can charge with solar/grid?
Or is this a pie in the sky project that's not worth it and buy the 8k gas boiler and forget it?
I realize a proper 48V battery back and inverter at this size quickly raises costs but I'm not in a hurry and would like to do it in stage such as:
-Boiler connected to grid and operating to understand accurate usage
-Battery pack and inverter powering boiler, grid charging battery pack
-Small solar grid connected to inverter to charge batteries and run boiler entirely
-Larger solar grid connected to inverter to charge batteries and run most of house?
I'm trying to use my flexibility that this is a backup system to develop a really nice setup without needing it to be running 24/7. I could see this growing into a grid tied system that eliminates my power bill.
Thanks for any advice.