If display is 55 degrees on vaillant boiler is that when boiler is at most efficient?
- Thread starter mrbg07546
- Start date
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That is the control for return temperature of underfloor heating, when it is serving to underfloor - I assume it uses another controller for the underfloor system.
I know it has been mentioning pump setting might be too high. But heat pump is set to auto..is this typically ok?
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What’s wrong with auto?
Ok it was actually set to 100%! I didn’t know. So I set it to auto. The actual value was 100%. I rebooted boiler put heating on and the actual value is still 100% despite being auto? Will it take time to tweak itself?
No, because it's auto based on 27kW when your system likely needs about 10kW
Ok given I have 13 radiators with trv averaging about 2.5 out of 5 shall I start with with 1? If it works leave it at that?
Ok I’ve set it to 1. I will check if anything changes. I will also report electricity usage as vsmart displays that
The gap between flow and return has increase by 2 degrees. When pump is at lowest setting (53%)
That’s disappointing because you would expect auto to modulate based on the change in resistance. Eg trv closed/open
A pump head of 1.97M will give 53% of the flowrate at 7M so would expect the rad(s) dT to double, your original dT was 4C? (47-43), so might have expected a bit more than 2C increase but rads with flow/return of 47/43C at a room temp of 20C, makes them 25deg rads which will only emit, (25/50)^1.3, 41% of that of their full 50 deg rating. Can you look at D.005, D.006, D.040 & D.041. Will find a few more parameters to look up later.
Also check D.00 & D.071
Also check D.00 & D.071
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Yes, forgot about the TRVs, because if in control will/should just open a bit more to maintain the same dT to give the same mean rad temp, flow target temp will have to be increased to 60C, this will/should then give a return right down to 30C when/if they throttle in, that's why/how one can get very low return temps by using them.
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I wonder if there might be any value in automating the flow and return temperatures and in some way throttling the circulation through the boiler and system, to optimise it?
If mrbg's boiler is a ecotec- exclusive 627 (or not) then after sorting out the above he might consider changing to Return temperature control, even if its designed for UFH control, so maybe worth giving it a go, if only out of interest.
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