CH bangs after new pump installation

[wolfwiser]

I have just had a new pump fitted to my Baxi Bermuda back boiler. The previous pump, according to the plumber the faulty pump was very old, probably original circa mid 70s?
The problem is now the heating pipes make banging and clanking noises when heating up, and periodically when switched on. This is different from the creaking due to expansion.
Prior to the new pump installation these noises didnt occur.
The highest radiator (towel rail type) requires a slight bleed every couple of days, but only for approx 5 seconds.
After reading previous posts it seems there could be air being pulled into the system or the pump is set at the wrong speed, is this the case and what is the best cause of action to stop being woken up at 5 in the morning (yeah, I know to keep the CH off!!)
FYI the boiler is downstairs, hot water cylinder is upstairs in the bathroom and all the other tanks are in the loft.
I have tried turning the boiler setting down a little which seems to help (now on 2.5 (out of 5), was on 3.5 before).

Thanks in advance for you help

 

[Softus]

I have just had a new pump fitted to my Baxi Bermuda back boiler.

Why by?

Why is that person not solving your banging problem?

The problem is now the heating pipes make banging and clanking noises when heating up, and periodically when switched on.

Is everything else OK?

Are you getting heat to all radiators?

Is the boiler spending less time on than before the pump change?

How did you go about venting the system?

Are there any auto-vents?

Did you fully open the pump valves?

Did the F&E cistern drain fully?

 

[Agile]

After reading previous posts it seems there could be air being pulled into the system or the pump is set at the wrong speed, is this the case and what is the best cause of action to stop being woken up at 5 in the morning (yeah, I know to keep the CH off!!)

Thanks in advance for you help

Odd that you dont tell us which speed its set to!

Virtually all pumps on domestic systems should be set to "2".

It sounds as if your system is now working properly whereas the flow was very restrictive before.

If its already on "2" the turn it down to "1" and see what difference that makes.

I suspect that the modern pump is just showing up latent defects in the system which were not apparent with the under performing old pump.

Tony

 

[twgas]

random banging and clanking on an old system may be an old anti-gravity valve,

 

[swbjackson]

Is the pump just for the heating? It could be that the pump is fitted on the return and the new pump has been fitted the wrong way round. I had this problem with a back boiler many years ago. A new pump had been fitted without noting which way the old pump was fitted. Turning it round solved all the problems.

 

[gas4you]

Is the pump just for the heating? It could be that the pump is fitted on the return and the new pump has been fitted the wrong way round. I had this problem with a back boiler many years ago. A new pump had been fitted without noting which way the old pump was fitted. Turning it round solved all the problems.

I agree, especially if you have old trv's that have to have the flow only one way through them

 

[wolfwiser]

Sorry about the delay in getting back.

Thanks for all of your input, will have a look at the pump speed, I'm sure its fitted the right way and I suspect that the new pump is just out-performing the old pump,

The majority of the noise seems to come from where the boiler is situated. I turned down the dial under the covering flap on the fire, which seems to have reduced the frequency of the banging, but it is still there.

It sounds a little like there is some localised boiling of water at the boiler which is 'bumping' (sorry I'm a scientist an thats the term I use when e.g. water boils within an oil).

All the rads work fine, as does the hot water which is also supplied by the boiler (HW storage tank in 1st floor bathroom).

I will have a look at the pump, wasnt sure how to adjust it, but as it sound like localised superheating could it be the pump is too slow? didnt want to mess around without some prior knowledge of what the settings should be...

Thanks all very much thus far...

 

[wolfwiser]

Just an update, hoping for a little more help. I have checked the smallest water tank in the loft which has a water level present as should be. I DO keep needing to bleed the radiators, but it seems there is no sign of any air getting dragged in by the new pump, only the upstairs rads though.

The radiator closest to the pump was partly closed (not the adjustable side), this after being open helped reduce the banging somewhat, but in order to stop it the boiler hasto be set to minimum, hopefully I havent effected the balance too much.

The new pump is set to II, with the flow facing towards the boiler, both the pumps inlet and outlet pipes seem equally hot so not sure if its on the right way? How can you tell?

Thanks in advance.