philiom

I cant see the customer wanting to pay up for that, its worked fine for 5 years and now its a problem, there going to say its down to me if we suggested that, space is not great either.

I know what you mean, its a fiddly job, been trying to think of a system that would open a zone valve to act as a bypass but the crossover time may be too short.

I have just had a thought about the issue of the possible flow problems, each pump has a 1 1/4" non return valve, it is a flap type unit as I have never seen the plastic internal one lasting very long. As there has been fresh water running through it, it may have caused the valves to stop moving fully, they are made of Gun Metal. Its something I will have to check, also it maybe the Honeywell auto by-pass needing a bit of adjustment, as you can imagine with having 2 - 15kw units it was not practical to use the three port valves, there are 4 zones ( 3 for heating and 1 for hot water) so its a big S plan (Honeywell Zone valves) and the microswitches in the valves are using the low voltage to switch the ASHP, it has all worked fine until now and its puzzling!!

Thanks!

I know I had the cover off a few times and know what you mean about the terminals!!

Hi, The system is not empty, its just got water in at the moment and its at 1.3 bar

Thanks for the info, really appreciate yours and Daves input. I have only been reading the flashes (9) on the red led on the board, I am a heating engineer so don't get too involved with the units themselves I usually get someone who knows how the internals work, I think its an external problem as the same fault is occurring on both units and I can't see two identical parts failing on two separate units at the same time.

The filters have been checked and clean ( they are on the return), its was a complete brand new system, one thing that had happened was the safety valves were passing and this was traced to the filling loop left switched on accidentally by the owner, it has lost all of its anti-freeze (Fernox HE15c) but dont think this is related to the problem with the flow, we have to reinstall fresh anti freeze, unless you think otherwise? All the radiators were sized for the temp of the air source and the cylinder came from Kingspan. The pumps are Grundfos UPS 32-870 180 and a new Honeywell By-pass was replaced when we had the issue with the flow switches about 30 months ago.

To GS Harris, thanks for the prompt reply, As I said to Dave we are going to try a few things on the system, you mention the controller, I have attached a pic of the controller and will try it on the 2 units.

Hi Dave, thanks for the prompt response, the pump speeds are on maximum, When it happened 30 months ago we did change the auto by-pass before we changed the flow switches but it turned out to be the flow switches , that is something I could look at, not sure if the pumps them selves are slowing down, I have measure the resistance and am going to get onto Grundfoss, the air source units were fitted in 2012, I have a controller we can set up and see what is happening.

We have a customer with 2 - 15kw Air Source Heat Pumps Model KHP0042, getting 9 flashes on pcb indicating flow switch issues, the only way it will restart is to turn of all power then it starts up for 5 - hrs and goes back to 9 flashes We had a similar fault about 30 months ago and we replaced the flow switches and it worked fine, tried new flow switches this time and it still has the same fault, when we had the fault the last time I could ring Kingspan technical for help, unfortunately they stopped supplying them and the tech help stopped, would appreciate any help or guidance.