Beads
All thumbs
I am largely handling some of the changes to my dad's hydronic heating system from over 1000 miles away. He is in central NY. Design temps must be subzero there. I am not DIYing this, but there seems to be significant boiler knowledge here. Please read on if you have the stamina.
Right now there is a 55 YO Crane Sunnyday boiler in place with an oil burner. Sunnyday has a DHW coil built in. I have oil use records going back several years. Gas has been in the house for some years running, sadly, only the dryer. Heavy rebates may be available (50% perhaps, 10% minimum) for an efficient boiler replacement. I've been learning about modulating and condensing systems. Apparently, the current boiler output is about 74 k. Heat losses have been estimated @ main 16 k, basement 12K and sun room 12 k for three separate zones.
Sun room is not used in very cold weather and has an exterior-grade door between it and the rest of the house. All zones are served with aluminum fin radiators. One exception is that in a kitchen reno the radiation was removed and a toe-kick heater was installed near the end of the main loop. It has been broken for a long time and installed in a less than accessible area. (A cabinet floor will have to be cut out to get to it. I suppose it should be fixed to lower the return water temp as much as possible.
Significant upgrades to the house have been made since built, insulation blown into walls, attic insulation improved substantially and windows improved. Basement was finished and split into a separate loop. (It was heated before the finishing off.) The sun room addition was built, well insulated and windowed, but heat was added later. Likely the radiation matched the need in that room pretty closely. Ditto for the basement, but the main zone is probably over-radiated for 180 F water.
Note that the three controls on the current boiler, according to a 15 YO grandson that is local, are set to 180, 170 and 160. I am guessing that 180 is the safety and the rest are high and low. The hour stays warm. There are three pumps, some combination of old modular, maybe B&G and some newer, smaller style.
It is a rural area and a BPI-trained and program-registered contractor must be used to get the rebates. Selection is limited. I got some proposals from some contractors before I knew of this requirement. I may be struggling with the decision of whether it is worth it to install a modulating boiler and the highest efficiency boiler or go with a cast iron boiler like the Weil Mcclain GV90+. I believe that the GV90+ meets efficiency (90+%) requirements for the program, but nothing much lower in efficiency does.
So far, everyone seems to want to oversize the boiler if the heat loss is correct. A Navien at 80 k is the smallest and some proposals, Triangle Tube, GV90+, Rinnai, and Baxi have specified boilers that are way larger than 73 k even though a smaller boiler in that line is available that is STILL larger than 73 k. I think that I am going to have to work hard to hold these guys' feet to the boiler and make them do this properly.
I know that a condensing boiler will not be any more efficient than a non condensing boiler if it is toggling on and off too much and I want to avoid that. I know that the zoning does not help with keeping the return water temp low. I know that with a modulating boiler, the more it turns down, the better shape I will be in. I don't yet know if any condensing boiler can be made to work well with the system. If not, I might as well choose the least complex, most robust boiler. I don't know what the best way to pipe the supply might be. I suppose that the contractor should be able to figure out how much of the time a modulating/condensing boiler will be in an efficient mode based on heat loss, boiler capacity and the radiation capacity. I don't know how best to handle the DHW supply. The way the the house is laid out, we may have to use the existing chimney with plastic pipe inside it to get the flue gas out. Adding a second vent for a separate hot water heater could be difficult with that constraint.
I'd love any general advice you may offer and any critique of my commentary. I have what might be a very naive question. The basement and main floor presumably need to be in separate zones for comfort since heat loss will not vary that much in the basement and will on the ground floor. There is not much of a thermal barrier between them, just a suspended ceiling under the joists. Given that is true, they should not be combined. If return water temperatures are too high to condense with a high efficiency boiler, could the zone that is not demanding heat serve as a heat "dump zone" to lower the return water temperature? It seems like it would not raise the temp in that zone excessively while increasing the efficiency of boiler.
Thanks, very much, for reading.
Right now there is a 55 YO Crane Sunnyday boiler in place with an oil burner. Sunnyday has a DHW coil built in. I have oil use records going back several years. Gas has been in the house for some years running, sadly, only the dryer. Heavy rebates may be available (50% perhaps, 10% minimum) for an efficient boiler replacement. I've been learning about modulating and condensing systems. Apparently, the current boiler output is about 74 k. Heat losses have been estimated @ main 16 k, basement 12K and sun room 12 k for three separate zones.
Sun room is not used in very cold weather and has an exterior-grade door between it and the rest of the house. All zones are served with aluminum fin radiators. One exception is that in a kitchen reno the radiation was removed and a toe-kick heater was installed near the end of the main loop. It has been broken for a long time and installed in a less than accessible area. (A cabinet floor will have to be cut out to get to it. I suppose it should be fixed to lower the return water temp as much as possible.
Significant upgrades to the house have been made since built, insulation blown into walls, attic insulation improved substantially and windows improved. Basement was finished and split into a separate loop. (It was heated before the finishing off.) The sun room addition was built, well insulated and windowed, but heat was added later. Likely the radiation matched the need in that room pretty closely. Ditto for the basement, but the main zone is probably over-radiated for 180 F water.
Note that the three controls on the current boiler, according to a 15 YO grandson that is local, are set to 180, 170 and 160. I am guessing that 180 is the safety and the rest are high and low. The hour stays warm. There are three pumps, some combination of old modular, maybe B&G and some newer, smaller style.
It is a rural area and a BPI-trained and program-registered contractor must be used to get the rebates. Selection is limited. I got some proposals from some contractors before I knew of this requirement. I may be struggling with the decision of whether it is worth it to install a modulating boiler and the highest efficiency boiler or go with a cast iron boiler like the Weil Mcclain GV90+. I believe that the GV90+ meets efficiency (90+%) requirements for the program, but nothing much lower in efficiency does.
So far, everyone seems to want to oversize the boiler if the heat loss is correct. A Navien at 80 k is the smallest and some proposals, Triangle Tube, GV90+, Rinnai, and Baxi have specified boilers that are way larger than 73 k even though a smaller boiler in that line is available that is STILL larger than 73 k. I think that I am going to have to work hard to hold these guys' feet to the boiler and make them do this properly.
I know that a condensing boiler will not be any more efficient than a non condensing boiler if it is toggling on and off too much and I want to avoid that. I know that the zoning does not help with keeping the return water temp low. I know that with a modulating boiler, the more it turns down, the better shape I will be in. I don't yet know if any condensing boiler can be made to work well with the system. If not, I might as well choose the least complex, most robust boiler. I don't know what the best way to pipe the supply might be. I suppose that the contractor should be able to figure out how much of the time a modulating/condensing boiler will be in an efficient mode based on heat loss, boiler capacity and the radiation capacity. I don't know how best to handle the DHW supply. The way the the house is laid out, we may have to use the existing chimney with plastic pipe inside it to get the flue gas out. Adding a second vent for a separate hot water heater could be difficult with that constraint.
I'd love any general advice you may offer and any critique of my commentary. I have what might be a very naive question. The basement and main floor presumably need to be in separate zones for comfort since heat loss will not vary that much in the basement and will on the ground floor. There is not much of a thermal barrier between them, just a suspended ceiling under the joists. Given that is true, they should not be combined. If return water temperatures are too high to condense with a high efficiency boiler, could the zone that is not demanding heat serve as a heat "dump zone" to lower the return water temperature? It seems like it would not raise the temp in that zone excessively while increasing the efficiency of boiler.
Thanks, very much, for reading.