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Last seen: Aug 24, 2026
@jamespa There are two 22mm flow and two 22mm returns shortly after rising from the heat pump where 25mm composite material pipework is used. I think ...
@jamespa Hello James and thanks again. The rads are connected in parallel and there are two runs of 22mm running down the sides of the house, in the...
@jamespa Thank you James, both for the comments and removal of my post made in error. Before answering your questions I think I should say that the...
@jamespa Thanks for your comment James. Of course you are correct and I think I was suffering a little brain fog in suggesting that the pumps were bot...
With the input from @f1p and @jamespa I am persuaded that my problems are all related to low available flow rate, particularly as I have a record of a...
@skyecraig Many thanks. Could you please describe where we are after carrying out any mods and what is necessary to restart?
Back working again now and problem was air in system. Flow rate is 17 l/min Answer to question re flow rate put to Mitsu UK (Portugal is useless): ...
@f1p Yes understand that but why. Investigating air in system
@jamespa Regretting I attempted this now. A very small amount of dirt in the filter, but L9 error now and won't start.
Is this a cross post with someone elses suggestion? I'm not sure we wanted to - i haven't checked the Hydrobox schematic as to see if there is a zone ...
@f1p I would appreciate some clarification on a few points: 1 At time of forwarding the Detailed Report the pump setting was 3 and the f...
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@toodles possibly. The £9k labour charge for 4-5 days w...
By AndrewJ , 4 hours ago
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RE: Plug and play solar. Thoughts?
My thought is simple. Bring it on and bring on plug in...
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RE: Heat Geek mini store vs pump size
Yes I agree, that’s why Heat Geek have most likely sele...
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RE: Who's your electricity provider and what's your tariff?
@chandykris Swings and Roundabouts, you win some…. ...
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@tomtheheatingengineer, thank you, and welcome to the f...
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RE: HeatGeek vs Octopus surveys: puzzling disparity - any ideas why?
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RE: Do I add Air Con or MVHR to existing A2W ASHP?
There is scope for product development here. I for one...
By JamesPa , 1 day ago
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RE: Is the "divide by 2900" rule still valid?
Really flow rate is a pipework limitation not a water p...
By JamesPa , 2 days ago
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RE: The good, the bad and the not that great – my heat pump installation
@burtis, I’ve followed this thread pretty much from the...
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RE: Starting Our Heat Pump Journey: 1962 build 3 bed detached house
First time poster here but I can share my experience as...
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RE: Is it the house or the equipment?
...which, I've found out, is pretty much impossible to ...
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RE: Mitsubishi Ecodan FTC6 settings
The Mitsi remote thermostat should not be plugged into ...
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