@johnmo Thank you for providing that clarification.

@editor  As requested a couple of photos. Many thanks for the information. It is so helpful to get that sort of clear information.

If I had a new ASHP installed I would still have to have a hot water cylinder. I watched the relevant video on this site. But I don't need any buffer unit. 

Can I get clarification on this point. 

Can the ASHP External unit, supply heat for Central Heating radiators or UFH at one temperature and one set of F&R pipes and do that supply directly? Bypassing the cylinder?

Or have I got that completely wrong and need to go away and do some serious reading? 🤔 

Nothing like a government grant to bring out the bandits for sure. An absolute minefield and as per my other post our current installation is hardly going smoothly. The company we went with however were one of the few who didn't want a massive amount of money (in effect the whole cost of the job minus the grant) up front, so at least I have some leverage to try and ensure it is completed to a decent standard.
As for optimus heating, came across as knowing their onions but I booked an initial home survey after a fair bit of back and forth communications (mainly telling me how good they were) and after all that they didn't turn up or contact me to tell me they weren't coming. Red flag #7?

@benson Optimus didn't turn up?

@editor Nope. Made a firm appointment, and they didn't turn up or make any contact. I was slightly miffed.

@benson that's very disappointing indeed.

Posted by: @gt22

↑

Can the ASHP External unit, supply heat for Central Heating radiators or UFH at one temperature and one set of F&R pipes and do that supply directly? Bypassing the cylinder?

Or have I got that completely wrong and need to go away and do some serious reading?

ASHPs (and fossil boilers running at a low flow temperature or with weather compensation - rare in UK, common in more enlightened countries) supply at one flow temperature at any one time and thus the installation will invariably include a three way diverter valve (or two two way valves) so that space heating or dhw can be fed, but not at the same time.  The unit switches flow temperature and the diverter valve according to whether space of dhw heating is required.

If you need, in addition, two flow temperatures for space heating you must supply the space heating at the higher temperature and mix down for the lower.  Again same for boilers and ASHPs.  The ASHP COP will be determined by the higher, because that is the temperature it is required to produce.

Hope that clears matters up.

@jamespa Many thanks. You are adding to my education on the current ASHP approach. So different from my 2009 Sanyo configuration, hence my questions.

Posted by: @gt22

↑

@jamespa Many thanks. You are adding to my education on the current ASHP approach. So different from my 2009 Sanyo configuration, hence my questions.

Great article! You've highlighted essential red flags to watch out for when considering a heat pump installation. One innovative idea would be to include tips on how to verify the credentials of installers, ensuring both quality and reliability in the installation process. Keep up the informative work!

↑

One innovative idea would be to include tips on how to verify the credentials of installers, ensuring both quality and reliability in the installation process. Keep up the informative work!

@mars That could be a whole discussion in itself.  I don't personally think its simple!