Boiler pump replaced but keeps coming on when room temp already reached

Albermarle

I'm also wondering if the old pump was so weak that it delivered the CH water so slowly that the system was naturally 'slow'! Now it has a new pump, the rads in that room heat up super-quickly, become very hot very quickly, and over-shoot? In which case the solution could be to turn down the pump speed - if that is a boiler option

In my limited experience heating engineers tend to set the boiler flow temperature too high, and the ( new maybe stronger)  pump speed on full. So as you say this might be the problem, the heating system is working 'too well' compared to before.

So reducing pump speed is worth a try, as is resetting the boiler flow temperature if it has been adjusted by the engineer.

Soconfused14

@Albermarle Would I have to get someone in to change pump speed. He told me it would be more efficient but usinmg more gas than ever.
@ThisIsWeird, should i turn tvrs down is this what you mean??

FreeBear

Soconfused14 said: Would I have to get someone in to change pump speed. He told me it would be more efficient but usinmg more gas than ever.

Newer versions of the WN Junior have a menu option accessible from the control panel that allows you to adjust the pump. Older models will be reliant on a switch on the pump (depending on make/model of the pump). Unfortunately, to get to the pump often requires the removal of the front casing, and you need to be Gas Safe registered to do this. That said, on some models, it looks like the pump is located below the room sealed part of the casing and may be accessible from underneath.

The best setting for the pump is the lowest speed that delivers heated water to the entire system - Smart(er) pumps can respond to different loads (handy when TRVs start shutting down), older dumb pumps just have I, II, and III settings. Start at I (lowest speed), then try II, but unlikely you will ever need III (max speed).

ThisIsWeird

Soconfused14 said:

@ThisIsWeird, should i turn tvrs down is this what you mean??

Ah-ha! I asked earlier what type of valves you have on the rads in the same room as the Digistat. Could you confirm, please?

The rads in the room with the room 'stat should not have TRVs on them, be it the hallway or (ideally) the sitting room.

It is important that only the room thermostat controls the temperature in that room, or else the two devices will 'fight' eachother.

So, if you do have TRVs fitted in that room, they should be opened to max, ie '5', and left like that - permanently 'on'. This way, they won't operate and affect the rads, so will allow the Digistat to do the temp controlling, as it should.

So, type of rad valves? And what are they currently set to?

ThisIsWeird

Soconfused14 said:

@Albermarle Would I have to get someone in to change pump speed. He told me it would be more efficient but using more gas than ever.

SoConf, can you recall what, exactly, the engineer said to you about this? Anything to do with pump speeds?

Soconfused14

So turning tvr down did not solve issue infact , it may be bit worse. Put heating on 18.5 and now is showing 19.5 and just fired up again. Time to call British gas I think cos this is not right.

ThisIsWeird

Soconfused14 said:

So turning tvr down did not solve issue infact , it may be bit worse. Put heating on 18.5 and now is showing 19.5 and just fired up again. Time to call British gas I think cos this is not right.

"So, if you do have TRVs fitted in that room, they should be opened to max, ie '5', and left like that - permanently 'on'."

ON! UP! To '5'! Remove its bleedin' head!

Soconfused14

@ThisIsWeird Yep all on 5 downstairs. 

Engineer said was a more efficient pump as ours was original with boiler 20 yeras ago.

Booked recall app with British Gas tomorrow so see what they say/do

Albermarle

Soconfused14 said:

@ThisIsWeird Yep all on 5 downstairs. 

Engineer said was a more efficient pump as ours was original with boiler 20 yeras ago.

Booked recall app with British Gas tomorrow so see what they say/do

That will be true but the pump runs off electric, so it will use less electric, not gas.
The issue is not the pumps efficiency but whether it is set at the right speed. Often they are on full speed unnecessarily.
It maybe be not connected to your 'stat issue' , it is just a guess 

ThisIsWeird

Soconfused14 said:

@ThisIsWeird Yep all on 5 downstairs. 

Engineer said was a more efficient pump as ours was original with boiler 20 yeras ago.

Booked recall app with British Gas tomorrow so see what they say/do

All TRVs should be set to provide the temp required in each room, except the ones in the same room as the room 'stat.
So, typically '3' for a roughly 19-20o room temp, if that's the desired temp for that room.
But, TRVs fully 'on' so that they effectively do not operate in the room where the wall stat is located. 
Please let us know what the engineer finds - it's an interesting one.