Can a central heating pump be too big for the system?

[WillsNana]

Can a central heating pump be too big for the system and what are the consequences?

Our system was fitted with a Grundfos 15-60 130 cat no. 1/44/215 which replaced a Terrier TC6 TF110 IP44 Class H . The engineer said it was a bigger pump and we had to turn it down to level 1 as it was pumping over.

We're still having some problems. Nowhere can I find the recommended pump sizes - not that it would mean a lot to me!

 

[gas112]

Yes a 15/60 can cause problems when replacing a 15/50 but if its pumping over on speed one that indicates another problem such as blockage or wrongly configured system

 

[doitall]

Agree with the above, a blockage in the cold feed or piped up wrong.

What is the height of the header tank above the highest point in the system.

more info required.

 

[WillsNana]

The header tank is in the loft. cylinder in bedroom below, rooms are 7ft high.

This has only happened since pump was replaced. It has run OK since Nov 2004 when new boiler, cylinder, rads installed. Could it be due to a slow moving motorised valve on the water? I switched off the cylinder stat to zero last night and we ran the ch all night on low. When the timer kicked in this morning it was ok.

We've noticed it happens when the timer switches on the hw and ch automatically.

 

[doitall]

Is it just a squirt when the pump starts/stops.

 

[WillsNana]

Don't know what you mean. I just turned up the cylinder stat which I'd left at 40 degrees but my husband said it was too cold. Within minutes bubbling hot water was pumping over into the overflow tank.

Husband switched off the heating, leaving the water on and it stopped bubbling

 

[doitall]

Was the pump fitted the right way round.

Can you post a pic or two around the cylinder, showing the pump and any valves/fittings.

 

[WillsNana]

I assume so. looking at the original plan of the pipework by the installers in 2004. The water comes out of the top of the boiler turns to the right behind a cupboard and down under the floor.

//www.diynot.com/network/WillsNana/albums/ All pictures I have are now uploaded (click on Pump folder). Spaghetti junction in pipework.

Another thing I wondered is that if the face of the red pump is up against the joist, how did the engineer get the air out? Isn't that where the bleed screw is?

 

[WillsNana]

The boiler is a Micron 70FF by the way, with an indirect hot water cylinder.


Could the problem be the motorised valve on the hot water?

 

[WillsNana]

Engineer came today and checked the valve. Is ordering a smaller pump.

We currently have heating on or heating switched off and hot water on. Can't have both.

 

[Meme21]

Yes a 15/60 can cause problems when replacing a 15/50 but if its pumping over on speed one that indicates another problem such as blockage or wrongly configured system

Hi - sorry to hijack this post- I was interested in this because I have been told that it might be best if I upgrade my pump from a 15/50 to a 15/60. What are the problems that could be caused?

 

[WillsNana]

No I don't mind at all. I just read your tale of the boiler installation.

We had problems when we changed boilers in 2004/5 (when I was Witzend on here - forgot my password). It was the guys on here that helped me sort it out... so please don't squabble like you did on Meme's original post.

We shouldn't have to sort this out ourselves but should be able to rely on the people that installed them. Everyone just washes their hands.

I found it incredibly stressful. Above all keep a log and take photos. You may have to refer to this all again!

By the way, it turned out my wall mounted boiler was plumbed in exactly as the floor mounted boiler had been. Once the plumbers swapped round the pipework, it started to work!

 

[Meme21]

We shouldn't have to sort this out ourselves but should be able to rely on the people that installed them. Everyone just washes their hands.

Yes - that has been my experience. As soon as paid, the gas engineer just didn't want to know, and yes again, we are the ones left to sort out any problems.

Glad you are getting sorted out, and I shouldn't moan too much, at least my house and hot water are warm even though I am woken up every morning by the CH system coming on.

 

[WillsNana]

It was Homeserve who installed the pumps. We're still suffering with it.

Got our regular plumber to look who thinks it could be one of the valves to the pump, not opening properly, so we'll try that next week.