Water Pump Flow Adjuster

[tmj9815]

Hi, can anyone help? I had my combi boiler fitted last year, and you just knew when the central heating switched on because of the noise from the whirring of the motor (could be heard in the living room, even though it's upstairs). My new girlfriend commented on this noise last night, so today I took off the cover (a Ravenheat combi) and located the pump. On top of the pump was a cigarette sized black box with a small dial on the side, with the settings I, II, III. It was set at III, so I adjusted it to I. The motor is now very quiet. Is there any danger to setting it this low? I also noted that I couldn't move the setting up to II (maybe because the water in the pump and boiler was still hot??). Thanks for any advice! And soz for messing with it. Yes, I know I should have left it alone, but it was Saturday night and she was moaning like a banshee !!

 

[ChrisR]

Leave it on 3 or you'll get problems. Firstly your HW will not be up to much. If the pump itself is noisy, you need a new one. If the boiler isn't very old you probably have a lot of dirt in there which has worn the pump out prematurely. Plumbers and DIYers who put in cheap and nasty combis usually take shortcuts elsewhere, like not bothering to flush a system properly.

 

[tmj9815]

Thanks Chris. The pump is a brand new Ravenheat pump that came with the brand new CH system, and it was making the same whirring noise it has made from day one. On this low setting it just sounds like a quiet motor. The CH works fine and the HW works okay too (pardon my ignorance, I didn't know the pump also worked the HW flow, I thought the pump was solely for the flow of the CH water). I'm thinking more of the long-term effects? In theory, a lower setting means the CH water just flows slower. A higher setting means the CH water flows faster, so in practice, I assume, a slower setting means the water just takes longer to heat up around the radiators. Anyone conquer, or should I hang up my plumbers overall now??

 

[DP]

You ask for advice. Chris gives good advice so follow it. He is a heating engineer. Combi boilers are fitted with pumps which are meant to run at maximum speed. You reduce the speed, boiler will overheat and hot water temperature will be effected. So will your warrenty. Your boiler is likely to be damaged as well.

Has the logbook been completed?

 

[tmj9815]

DP, first off, I know I asked for advice. Thanks for pointing that out to me. Second, I'm very grateful for the advice Chris has given and any other advise received. As I know nothing about boilers (IT background), this is why I ask the questions. If this were an IT forum, I'd spell it out so that anyone could understand.

So, why does a combi boiler come with a three-speed pump? Surely if it's made to run at max speed, God would have created the pump with no speed adjuster.

This morning the heating came on as normal without me or the other half waking up to the whirring noise. The HW came out of the shower at the same speed and same heat. I looked at the boiler, checked the heat coming from the radiators, checked the pressure gauge, and all seems to be running fine. The HW setting has always been on the lowest setting.

I have also received an email from a mate who also experienced a loud whirring noise similar to mine from his brand new combi, fitted last month. The plumber who fitted it came out and simply reduced the pump from ‘III’ to setting 'I'. The noise apparently, has disappeared.

Log book, what log book ?