Alternety
Like an engineer
I need to replace a primary circulator pump in a hydronic system. It is a Grundfos UP-26-64 P. I am just looking for a correct max pump pressure and flow rate. I am not convinced that it is operating at the proper place on the pump curve. I understand the nasty variables in reaching this objective.
I have a couple of configuration programs, but they are too orientated toward a total system design. They require a whole bunch of detail I do not really want to recreate. I have not found a way around a full design. I just need to do a couple of iterations to see if the current pump is in the correct ballpark. I believe the loads below are too high, but the tools I have do not include loss parameters that match the design. I had a full design, but I lost it when a motherboard crashed. The installed system pretty much matched my design, but it was 10 years ago. And the details are lost. I understand the chance of everything demanding heat at the same time is fairly small. Most of the issues I have with the system are at low flow rates.
Here is what I need to be able to do. I am pretty much re-doing the piping for the main distribution assembly. I am doing this because of what I consider to be a serious failure of Viega compression fittings (i.e., they all leak and look really crappy, but not as far a Viega is concerned). In addition, the configuration is not compatible with an ability to properly flush the system or replace degradable components. I am going for a gross number. I just want to get a sense of whether the existing pump is too big/small. I want to use a variable speed pressure sensing pump.
- Assume 1/2" PEX, at a rational spacing, heating 2 X 3000 sq ft. (larger PEX to 5 manifolds)
- Assume 26 zones. Some are quite small, others large. Average is likely to
be a reasonable approximation.
- Heat loss max 40,000 BTU/hr. Too high, but a starting point for iterations.
- Fluid is 50% Polyethylene Glycol.
- Condensing boiler with a target of < 130 F.
If someone could point me to a suitable tool or set of calculations I would greatly appreciate it. I need to get this resolved. It is starting to get cold (Yeah, I know. But it was not that simple).
I have a couple of configuration programs, but they are too orientated toward a total system design. They require a whole bunch of detail I do not really want to recreate. I have not found a way around a full design. I just need to do a couple of iterations to see if the current pump is in the correct ballpark. I believe the loads below are too high, but the tools I have do not include loss parameters that match the design. I had a full design, but I lost it when a motherboard crashed. The installed system pretty much matched my design, but it was 10 years ago. And the details are lost. I understand the chance of everything demanding heat at the same time is fairly small. Most of the issues I have with the system are at low flow rates.
Here is what I need to be able to do. I am pretty much re-doing the piping for the main distribution assembly. I am doing this because of what I consider to be a serious failure of Viega compression fittings (i.e., they all leak and look really crappy, but not as far a Viega is concerned). In addition, the configuration is not compatible with an ability to properly flush the system or replace degradable components. I am going for a gross number. I just want to get a sense of whether the existing pump is too big/small. I want to use a variable speed pressure sensing pump.
- Assume 1/2" PEX, at a rational spacing, heating 2 X 3000 sq ft. (larger PEX to 5 manifolds)
- Assume 26 zones. Some are quite small, others large. Average is likely to
be a reasonable approximation.
- Heat loss max 40,000 BTU/hr. Too high, but a starting point for iterations.
- Fluid is 50% Polyethylene Glycol.
- Condensing boiler with a target of < 130 F.
If someone could point me to a suitable tool or set of calculations I would greatly appreciate it. I need to get this resolved. It is starting to get cold (Yeah, I know. But it was not that simple).