Noisy pump in brand new Worcester Bosch Junior 28i Combi

[militarymartin]

Hi,
I've recently switched over from warm air to a wet system (Worcester Bosch Junior 28i combi, 8 rads (3 TRV)). The installation went OK. However, when the system was commissioned there was what I considered to be an excessive whine (sounds like the next door neighbour constantly hoovering) coming from the boiler, which travels throughout the system. It transpires that the noise is being caused by the pump.
A WB engineer was called out, who replaced the pump. However, this made no difference whatsoever, so the engineer turned the pump down to its lowest setting, and arranged for their technical bod to come out. Although the lower setting got rid of the noise the pump was now unable to circulate the water fully round the system and some radiators were only luke warm.
The technical bod came out, replaced the pump again, checked over the boiler, and basically said there was nothing more that they could do.
Although it appears that the noise has reduced since the third pump was fitted, I'm not sure if it actually has or if I've just got used to the noise.
Has anybody else experienced similar problems?
Any ideas what's causing this noise?
Looking forward to your posts.
Best regards
Martin

 

[COG]

Has your installer fitted any kind of auto by-pass on the system and does the noise change if you turn off the 3 trv's. Do you no if the worcester eng checked the isolateing valves were clear

 

[AnonymousImport]

Do not need a by pass system on a combi, they usually have built in ones. Have you checked if TRVs are on the flow, to do this turn all rads off that have TRVs, let them and the pipework cool down. Turn boiler on and open them up one by one and see which pipe gets hot first. The pipe with the TRV should get hot first.

Possibly could be caused by solder in the pipe work, do you get a tinging sound in the pipes?

Also is the automatic air vent open on the boiler?

 

[Registered Gas Man]

Does sound as COG describes

Do you no if the worcester eng checked the isolateing valves were clear

Although I can't see why the WB eng would come out and replace a pump if its a system design problem!!! As they are only concerned with the Boiler, I'm sure they havent checked the system throughly.

As COG decribes does the boiler have an internal bypass or an external bypass fitted?.

I assume the boiler was fitted to an old system was it flushed correctly before installation?

Are the TRV's new? If so are they reversible (it's safe to assume that almost all new valves are reversible!! I Hope ), if this is the case jo.m's tests are redundant they dont have to be fitted to the feed side.

Is your system balanced? A lower pump speed should heat the house in a longer time, not stop some rads getting heat. Search the forums for system balancing and follow the instructions then turn the pump speed down and see what happens? You should have no noise and heat to all rads.

 

[militarymartin]

Hi,
Thanks for the posts.
The whole system (heating side) is brand new, as it replaced a warm air system. The DHW was originally supplied by a multipoint, which was replaced by the combi. The hoovering noise is not there when water is drawn from the DHW side (only noise you hear when you're next to the combi comes from burner/fan, which are very quiet compared to the hoovering noise). The TRV's are reversible. Don't know about a by-pass, but if it's in the boiler would have assumed the WB people checked this out when they changed the pumps.
Anymore suggestions that I can pass onto the installer/Worcester Bosch?
Looking forward to your posts.
Best regards
Martin

 

[COG]

Worcester would have replaced the pump to prove to the installer it was not a boiler fault. The Worcester eng will try not to investigate the system just fix the boiler, he has to try and be diplomatic without upsetting the installer (his real customer) .check with your installer to see if he fitted any kind of by pas auto or manual regardless of if it needed it or not. The junior uses a very sim heat ex to the one on the 28si I have had one of those make a noise like a demented banshie (ex wife ) in ch mode from new. If the worcester eng says hes never had one do that before remind him the junior has only been out 2 months. To test the heat ex run the boiler on CH with the gas shut off if it still makes the same noise shut off both bulkhead valves and see if it continues if it does it has to be the heat ex but if its only noisy with the heat on you cant test it just replace it.