loudipierro
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- Mar 7, 2023
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Hello all. I am currently in the process of selecting equipment for a new Combi boiler that I am installing in my home. I am a boiler technician but I work with large industrial steam boilers mainly, and mostly with controls. I am not a hydronic expert. But I have done a lot of residential plumbing and HVAC work. I am either going to go with the Laars FT series (140k BTU) or the Bosch Singular 4000 (155k), both are priced the same and are roughly the same size. I'm actually not sure which one to go with but thats a topic for another thread. If any of you guys have a preference between those two brands please let me know.
However, the reason I created this thread and what I am having a little bit of difficulty with is selecting a circulator. I've taken measurements and done the head loss calculations, but its very close so I'm really not sure. I just wanted to get some opinions on this. Here are the details about my house and heating system:
Home is about 2000 sq ft of heated space, 4 heating zones all with 3/4" zone valves.
Zone 1 is radiant floor in the original concrete slab which is a total of about 850 sq ft. There are 4 loops, each one about the same size and consisting of about 80-100 feet of 1/2" copper tube in the concrete. I am putting in a new 4 loop stainless manifold to supply the 4 loops. The manifold itself is going to be supplied from the zone valve with 1" PEX (supply and return) and is about 40 feet from the zone valve (so 80 feet of 1 PEX total). There will be very few, if any, fittings in the PEX.
Zone 2 is two sections of 3/4" fin tube, each section is about 14 feet long. There is a tee splitting into the two sections and the Tee will be supplied from the zone valve by 1" PEX. Again about 80 feet total of 1" PEX with no fittings.
Zones 3 and 4 are virtually identical - each of them is about 28 feet of 3/4" fin tube supplied from the zone valve with 3/4" copper (less than 10 feet of it in both cases).
Clearly the radiant floor represents the largest head loss here, from my calculations about 7 or 8 feet of head total (worse case). The pump I would like to get is the Grundfos Alpha 1 but I'd like to get opinions on that and see if you guys think it will be sufficient. If you look at the curve you will see that it probably will not supply quite enough flow for all 4 zones at the same time but my thinking is this: the radiant floor runs for a while to heat up the concrete slab, but once that happens, the zone hardly ever calls for heat. Once the whole slab is warmed up, the zone only calls for a few minutes at a time every once in a while (not very often). When the radiant isn't calling, the fin tube zones will have plenty of flow available with that pump. The reason I want this pump is because it changes its speed to maintain a constant pressure, its very efficient. Neither Grundfos nor Taco make a more powerful pump that is available with the constant pressure control. In order to step up to a pump that I KNOW would be more than enough, I'd have to go with something like the 1/6 HP Grundfos UPS26-99, which I feel is overkill for my house.
However, the reason I created this thread and what I am having a little bit of difficulty with is selecting a circulator. I've taken measurements and done the head loss calculations, but its very close so I'm really not sure. I just wanted to get some opinions on this. Here are the details about my house and heating system:
Home is about 2000 sq ft of heated space, 4 heating zones all with 3/4" zone valves.
Zone 1 is radiant floor in the original concrete slab which is a total of about 850 sq ft. There are 4 loops, each one about the same size and consisting of about 80-100 feet of 1/2" copper tube in the concrete. I am putting in a new 4 loop stainless manifold to supply the 4 loops. The manifold itself is going to be supplied from the zone valve with 1" PEX (supply and return) and is about 40 feet from the zone valve (so 80 feet of 1 PEX total). There will be very few, if any, fittings in the PEX.
Zone 2 is two sections of 3/4" fin tube, each section is about 14 feet long. There is a tee splitting into the two sections and the Tee will be supplied from the zone valve by 1" PEX. Again about 80 feet total of 1" PEX with no fittings.
Zones 3 and 4 are virtually identical - each of them is about 28 feet of 3/4" fin tube supplied from the zone valve with 3/4" copper (less than 10 feet of it in both cases).
Clearly the radiant floor represents the largest head loss here, from my calculations about 7 or 8 feet of head total (worse case). The pump I would like to get is the Grundfos Alpha 1 but I'd like to get opinions on that and see if you guys think it will be sufficient. If you look at the curve you will see that it probably will not supply quite enough flow for all 4 zones at the same time but my thinking is this: the radiant floor runs for a while to heat up the concrete slab, but once that happens, the zone hardly ever calls for heat. Once the whole slab is warmed up, the zone only calls for a few minutes at a time every once in a while (not very often). When the radiant isn't calling, the fin tube zones will have plenty of flow available with that pump. The reason I want this pump is because it changes its speed to maintain a constant pressure, its very efficient. Neither Grundfos nor Taco make a more powerful pump that is available with the constant pressure control. In order to step up to a pump that I KNOW would be more than enough, I'd have to go with something like the 1/6 HP Grundfos UPS26-99, which I feel is overkill for my house.