Any ideas? Unreliable heating.

[garyevans]

Heating issues. Had new water pump fitted 3 weeks ago, new 3 port valve 18 months ago, boiler is 4 years old. I balanced radiators when new pump was installed and for 2 weeks or so the heating and hot water worked a treat. 3 days ago, woke up to find neither working properly. Timer comes on, boiler fires up but radiators downstairs not getting warm. Hot water not great. Balanced radiators again and all was fine but last two days every time I turn heating on nothing warm downstairs in spite of balanced radiators two days ago working fine. Pump does seem to work fine when it runs quietly but each time it starts there is a whirring noise and you know it won't work properly. Any ideas?

 

[ShaunCorbs]

What’s the make of the pump ?

 

[garyevans]

What’s the make of the pump ?

Grundfos

 

[ShaunCorbs]

Grundfos

Black one or red one ?

 

[garyevans]

Black one or red one ?

Black

 

[John.g]

Is it this one?, if so post a photo of the LEDs while running.

 

[ShaunCorbs]

Ups3 any red lights when running / having problems?

 

[garyevans]

Is it this one?, if so post a photo of the LEDs while running.
View attachment 79947

 

[garyevans]

View attachment 79949

Radiators are bled, upstairs all hot but nothing downstairs. Inlet valves are warm but nothing getting into rads. All balanced 2 days ago and working fine.

 

[John.g]

How many rad? and is it a sealed or open vent system with a Feed&Expansion (small) Tank in the attic.
If a sealed system ensure that the system pressure is 1.5bar cold.
If a OV system, present setting of CC3 at 6.4M is too high IMO and can cause air ingress.
Suggest, in either case, c/o to constant pressure setting 2, CP2 which is 4.5M.
Press the setting button for ~ 3 secs until the yellow LED illuminates at the far right, then briefly press the button until the green LED and the yelloe LED next to it are also illuminated, you are now on CP2 at a constant 4.5M head.

(Also, these pumps have had more than their "fair" share of failures.)

 

[garyevans]

How many rad? and is it a sealed or open vent system with a Feed&Expansion (small) Tank in the attic.
If a sealed system ensure that the system pressure is 1.5bar cold.
If a OV system, present setting of CC3 at 6.4M is too high IMO and can cause air ingress.
Suggest, in either case, c/o to constant pressure setting 2, CP2 which is 4.5M.
Press the setting button for ~ 3 secs until the yellow LED illuminates at the far right, then briefly press the button until the green LED and the yelloe LED next to it are also illuminated, you are now on CP2 at a constant 4.5M head.

(Also, these pumps have had more than their "fair" share of failures.)

I think it is an open vent system. I have no way of setting system pressure and I know there is a small tank in the attic. We have 5 rads upstairs and 7 downstairs. I will follow your instructions and see how we get on. Cheers.

 

[EvilDrPorkChop]

Pumps set too high and probably drawing air in, causing your downstairs circuit to air lock. The new Grunfos ones are more powerful than the old, you'll probably easily get away with I or II on the new model.

 

[garyevans]

Pumps set too high and probably drawing air in, causing your downstairs circuit to air lock. The new Grunfos ones are more powerful than the old, you'll probably easily get away with I or II on the new model.

Thank you. Lights now flashing like in screenshot on Constant pressure 2. Should I restart system to deal with airlock downstairs?

 

[EvilDrPorkChop]

Thank you. Lights now flashing like in screenshot on Constant pressure 2. Should I restart system to deal with airlock downstairs?View attachment 79951

Bleed any rads. Turn HW on, on it's own. Let it circulate round the HW system. When Hot and returning, turn HW off and CH on. Let upstairs rads get hot, when they're hot turn them all off and it should force it through to downstairs.

See how you go on 2, if it keeps airlocking you may need to turn it down to 1.

 

[John.g]

When you have done the above go up to the attic and get someone to stop the boiler and watch and see if any spurt of water from the vent when the pump stops probably a few minutes after switching off the boiler, then get them to restart the boiler/pump and watch again for any pump over.

 

[garyevans]

Bleed any rads. Turn HW on, on it's own. Let it circulate round the HW system. When Hot and returning, turn HW off and CH on. Let upstairs rads get hot, when they're hot turn them all off and it should force it through to downstairs.

See how you go on 2, if it keeps airlocking you may need to turn it down to 1.

Thanks to both of you. Issue now sorted. You have been a massive help!!!

 

[John.g]

Glad you are sorted.
Some OV systems with the traditional V,C,P system still have problems with air ingress with a pump head > than say 3.5/4.0M that may be required for systems with a large number of rads or small bore piping can be "cured" by changing the above to a combined vent and cold feed like my 50 year old system (from new), I could run my system with one rad and still get no carry over at a pump head of 6M.

 

[garyevans]

Glad you are sorted.
Some OV systems with the traditional V,C,P system still have problems with air ingress with a pump head > than say 3.5/4.0M that may be required for systems with a large number of rads or small bore piping can be "cured" by changing the above to a combined vent and cold feed like my 50 year old system (from new), I could run my system with one rad and still get no carry over at a pump head of 6M.

Cheers. I am no plumber so much if that is like a different language. Sadly, it seems that as predicted CP2 might still be too much. Good heat last night, this morning but this evening after about 3 hours, I could hear a different 'tone' in the pump and once again the downstairs rads went cold. Trying to change to CP1 and go through same steps as last night. Bloody nightmare.

 

[John.g]

Its quite likely that you have a partial blockage where the cold feed joins the system, if you still have a problem at CP1 @ 3M then almost a certainty IMO. Any idea of the old pump (and setting).

 

[garyevans]

Its quite likely that you have a partial blockage where the cold feed joins the system, if you still have a problem at CP1 @ 3M then almost a certainty IMO. Any idea of the old pump (and setting).

This was the old pump. Was mostly on second speed but more recently 3.

 

[garyevans]

This was the old pump. Was mostly on second speed but more recently 3. View attachment 79992

This is what the pump was doing as I switched HW off.

 

[John.g]

I'd say speed 3 was running at; at least a 5M head, can you check the direction of flow on the UPS3, if your system is something like the attachment, then the arrow on the pump should be pointing downwards.

 

[garyevans]

I'd say speed 3 was running at; at least a 5M head, can you check the direction of flow on the UPS3, if your system is something like the attachment, then the arrow on the pump should be pointing downwards.

The pump was upside down so the picture I sent is after I have rotated it

 

[garyevans]

The pump was upside down so the picture I sent is after I have rotated it

Where is the arrow?

 

[John.g]

The pump was upside down so the picture I sent is after I have rotated it

What do you mean by upside down? the pump label etc may be upside down but all that matters is that the arrow on the pump body is pointing in the correct direction.
Your picture is only darkness.

 

[John.g]

Where is the arrow?

On the pump body, will send photo.

 

[garyevans]

What do you mean by upside down? the pump label etc may be upside down but all that matters is that the arrow on the pump body is pointing in the correct direction.
Your picture is only darkness.

The picture of the old pump (blue) is rotated. The writing on it was upside down. It was the pump installed when the house was built.

 

[John.g]

Just to the left of the cable socket, on the pump body.

 

[garyevans]

Just to the left of the cable socket, on the pump body.

View attachment 79997

Yes, it is pointing downward

 

[John.g]

So, are you absolutely certain that the new pump is pumping in the same direction as the old one, ie, the arrow on the old pump was also pointing downwards??, Is you system as I showed above or can you post a photo of it?, its strange that you are getting problems at CP2 even though it is a bit high so CP1 may sort out the problem, was that system chemically cleaned or anything like that between pump changes?.

 

[garyevans]

So, are you absolutely certain that the new pump is pumping in the same direction as the old one, ie, the arrow on the old pump was also pointing downwards??, Is you system as I showed above or can you post a photo of it?, its strange that you are getting problems at CP2 even though it is a bit high so CP1 may sort out the problem, was that system chemically cleaned or anything like that between pump changes?.

This is the old pump and if it appears you will see what I mean by upside down. I don't have any other image so can only presume the British gas engineer who put the new one in ensured it is pumping on same direction. No chemical cleaning I am aware of.

 

[John.g]

Well you will have to be happy (ensured) that the UPS3 is pumping in the correct direction before taking any drastic or unnecessary action, if the pipe coming out of the bottom of the pump then goes to either a three way valve or to a number of valves (all/any of which will have a motor with a cable) then pump direction is downwards, if these valve(s) come off the top pipe then the pump must pump upwards.

 

[garyevans]

Well you will have to be happy (ensured) that the UPS3 is pumping in the correct direction before taking any drastic or unnecessary action, if the pipe coming out of the bottom of the pump then goes to either a three way valve or to a number of valves (all/any of which will have a motor with a cable) then pump direction is downwards, if these valve(s) come off the top pipe then the pump must pump upwards.

Yes, that's where the 3 port valve is

 

[John.g]

so 3 port below pump and pump pumping downwards is correct, CP1 or just maybe PP2 next step??

WhT was happening when the pump was stopping as can't see it

 

[John.g]

Your old pump was probably a 6M Selectric (made in 2007) so the pump curves may look like this. If so then even speed 3 has a relatively low head of 2.5m at 0.7ms/hr and hopefully CP1 or PP3 will also not cause any pumpover problems.