Problem with Grant Combi Boiler - no hot water

[Terrywookfit]

The head will rotate to get wiring in correct position if allen screws are removed.
Double check with pump you removed for direction,

 

[Terrywookfit]

A photo of the old and new would be interesting.

 

[Charon71]

They're identical wilo pumps, I literally swapped one for the other but didn't rotate the head to line anything up - just wired it in. Wondering if I might have knocked some limescale loose while fitting it which has caused a blockage?

 

[Terrywookfit]

You need to check that the arrow denoting flow direction is same as NRV flow.

 

[ianmcd]

Must agree if you swapped the whole pump and not just the head then it sounds like it is upside down, very easy to do, and as said you need to check the arrow on the pump body , and agree some pics would help

 

[Andy4444]

As said above I would be looking at the pump.

Did you change just the pump head or did you change the base plate of the pump as well?

Out of the box, these pumps fitted with the electrical connection facing up and the direction of flow is also up. For the hot water pump on the combi, the head of the pump needs to be rotated 180° in order to fit into the boiler and the direction of flow (arrow is on the rear of the base plate) must be down.

So if you changed the entire pump and not just the head make sure the arrow on the base plate is pointing down.

 

[Charon71]

Thank you all for the replies however I'm 100% sure the pump is in the right way. Due to the design of the pump (the electrical connections are on one side) it won't physically fit the other way up, plus I simply took the old one out and replaced it with an identical one, installing it in the same position.

I've just thought though, when I installed it I noticed that the live wire was dulled after the previous pump burnt out - its definitely getting power, could it be it's not getting enough due to the condition of the wire?

 

[JohnD]

The pump, and the motor assembly with the connections, can be rotated against each other.

So you are wrong to assume that the orientation of your old pump is the same as your new, just because the connections are.

 

[Andy4444]

Thank you all for the replies however I'm 100% sure the pump is in the right way. Due to the design of the pump (the electrical connections are on one side) it won't physically fit the other way up, plus I simply took the old one out and replaced it with an identical one, installing it in the same position.

I've just thought though, when I installed it I noticed that the live wire was dulled after the previous pump burnt out - its definitely getting power, could it be it's not getting enough due to the condition of the wire?

Did you just charge the pump head or the whole assembly?

 

[Charon71]

The entire pump, I literally disconnected it, pulled it out and put the new one in exactly the same position

The new pump is identical to the old one (make, model etc)

 

[Andy4444]

Which way is the arrow pointing?

 

[Charon71]

Am at work so will need to check the direction when I get home, but I looked at the old one and new one last night to confirm that they are completely identical - direction of arrows included!

Will update on the direction tomorrow as am away with work tonight

 

[Andy4444]

They may look identical but they come out of the box not necessarily with the pump and volute in the correct orientation for the Grant Combi.

I got bit on the arse by the exact same problem with the exact same symptoms you describe.

Just rule this out by simply by checking the position of the arrow

 

[Charon71]

Will do, thanks for that. Will report back tomorrow

 

[Terrywookfit]

Thank you all for the replies however I'm 100% sure the pump is in the right way. Due to the design of the pump (the electrical connections are on one side) it won't physically fit the other way up, plus I simply took the old one out and replaced it with an identical one, installing it in the same position.

I've just thought though, when I installed it I noticed that the live wire was dulled after the previous pump burnt out - its definitely getting power, could it be it's not getting enough due to the condition of the wire?

You said that there was 240 at pump terminals when I asked earlier !!