Hybrid ASHP with oil fired boiler.

[MichaelPD]

Hello. 

I am new to this so forgive me if this is something that others have already asked.

 

I installed an ASHP two years ago, I had/have an oil fired boiler, and because it was only a few years old the plumbing engineer and I decided to combine the two into a hybrid system. Both Boiler and ASHP are Grant. Grant had a 'crossover' system in place to accommodate the two different heating systems. 

 

I also have a Solar PV system and battery storage to complement the ASHP.

 

I had hoped that the system would be relatively easy to use, and I guess it is. But, I am struggling again to get one of my rooms (the one furthest from the heat source ) up to temperature. 

 

I had used the Hive thermostat (down stairs, up stairs, and DHW) on a schedule up until a few days ago, and decided to just have it ON for upstairs and down stairs to see if it made a difference, which it doesn't. 

 

When the DHW comes on schedule, then the temperature drops, this is acceptable, but it keeps dropping. I have no way of knowing how long it takes to heat the DHW and was told that even if the DHW was ON for say six hours, the System would 'sense' that the DHW was at temperature and would divert to CH again. But it looks like this is not the case? 

 

Because of the cold snap at the moment I don't want to risk having the DHW switched to ON incase it cools the house and take too long to switch back to schedule. 

 

So the short question is how should I schedule, or not the DHW so that there is NO drop in temperature in the house. 

 

Lastly, is there any forums with people in the same situation as myself? Struggling for information and help with these kind of systems. 

 

Thanks

 

Much appreciated 

 

 

[JohnMo]

Suspect you have a couple of different issues. Radiator not heating sufficiently is likely radiator balancing issue. So more water going through the first radiators in the circuit and not making it the last one. So system needs to be balanced - or system needs a higher flow rate. A grant ASHP uses a flow setter valve maybe the plumber hasn't set this correctly. In the ASHP instructions it says how these are set up.

 

Grant do stuff in a slightly strange way to make a plumber happy in most cases. So could be a wiring issue. I would make an effort to understand what is happening when the cylinder calls for heat and when it's up to temperature does it automatically switch back to heating. Find out what valves move or don't move at either end of the cycle. An easy way to do this is turn the cylinder thermostat down then select cylinder heating on the timer. On selection of heating via timer nothing should change, if it does you have a wiring issue. If central heating stays on all good. Then wind the thermostat up so you get a call for heat and see what moves and doesn't, then wind the thermostat down to put heat off does valves go back to original position. At this point the central heating should be back to normal - if it doesn't there is a wiring issue.

 

When you DHW heating is that in hybrid or ASHP or oil boiler?