I have just purchased a smart pump to go with the ASHP system I'm putting in and the main difference seems to be that rather than selecting a speed you select one of three bands within the pump curve. I presume this means that the pump modulates to give the same head as TRV's open and close rather than generating unnecessary pressure when flow drops.
When deciding to install an ASHP using the existing radiator system I opened Pandora's box. Because of improved insulation my existing radiators were over sized so I thought they would be big enough, but when I looked in detail they weren't. To get a decent COP you need to get the water temperature right down and I've ended up changing most of them. This need not be particularly difficult or expensive, you can often get higher thermal outputs by changing to double panel or going taller and still using the same supply and return pipes. Also, you need to keep the temperature drop through the system small so you need to have high flows so decent pipes and distribution. I've made sure that at maximum heat load the flow is sufficient to give a temperature drop of less than 4C.
I've actually ended up putting on more TRV's. The ASHP is basically controlled from the outside temperature and should adjust the radiator temperature to suit. This can be biased by a room stat. However, we have a log burning stove and many of the rooms benefit from solar gain and certainly will not need heat on cold sunny days whilst north facing rooms will. So if you want to automatically decrease your heating (and bills) you need to address this and the obvious solution is TRV's.
I suggest you think hard and long before going down the ASHP route and don't necessarily believe potential suppliers. I've found the level of expertise to be generally low and this was reflected in the performance levels reported by the Energy Saving Trust produced a while back. However, I'm convinced a properly designed and installed system can give good results.
Having said all that I'm still a theorist and will only get results when the system is commissioned next month!
Don I have been testing how my system works at low water temperatures all winter. I have computer control of my boiler, pump and zones with temp readings in all rooms so it's been quite easy to do.
I have found it to work well at a minimum of 43c flow temp with the system working 24/7 with a couple of degree setback overnight.
As we are retired this suits us very well.
To keep the house warm with these water temps it does need to keep the house from cooling down too much. So I know that it works well. In fact we have never felt so comfortable. I will increase sizes of a few of the rads so maybe I'll be able to cut the water temp down a bit more I'm not sure.
I'm terrible at maths and don't have much idea about the technical side. I have no idea how to check pressures, flow rates etc but obviously I need to get up to speed on that to choose my new pump wisely.
I don't really understand what " select one of three bands within the pump curve" means lol
I cant change my pipework any more than I have done to improve circulation but what I did find was that this system was installed by an idiot!
So I had to increase the main pipes to the distributor as they were in 15mm !! , I also increased pipe size to furthest away rads but this was all that was possible without major concrete floor upheaval! I also increased pipes from Boiler to 28mm.
I understand that ASHP systems need a good flow rate to shift the low grade heat. So i did think maybe it's best to keep my present pump until I did some overnight testing of my electric consumption because it was so high and found out it was nearly all down to the pump.
Thats one reason I decided to get rid of the TRV's though as I read they can cause problems if they all start shutting down.
I'm not sure of the technical reasoning though ?
I looked at the type of pump you talked about as they are supposed to save about 80% of electric. They look very expensive though!
what did you pay for yours?