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Water source heat pumps- please advise
I looked at a project today with water source heat pumps. They are supplied with hot water by an 800,000 btu steam boiler connected into (2) 11/2 steam to water heat exchanger plates. The heat exchangers are 11/2 and both connect into a common 11/2 header before tying into 4 inch supply and return mains feeding the various heat pumps throughout the building. Is this a bottleneck and not allowing the full flow of the heat exchangers and boiler?
I am not familiar with heat pumps. The contractor that showed me the job wants to replace the steam boiler with a conventional cast iron hot water boiler and pipe direct to the heat pumps. He further explained that the boiler water needed to supply the heat pumps is in the range of 80-110 degrees. If this is correct, this return water temp is too cool for a conventional boiler and I advised against this.
I considered multiple mod cons, but the venting is nearly impossible. So, I have also considered a 4 way mixing valve, variable speed injection pump, bypass piping or a water to water heat exchanger to separate the boiler from the system and provide boiler return water protection.