Central Heating Water hammer

[Gwyn1]

Hi, I am looking for some advice on an annoying water hammer ? problem in my central heating system.

Although the system appears to be working OK, whenever one of the radiator fitted Honeywell thermostats is in the act of switching the water off at its preset temperature, I get a low rumbling throughout the house for about half an hour.

This happens on three of the radiators in the house, and if I turn the temp up or down on the offending radiator stat, the rumbling stops immediately.

Should I get the three Stats replaced or do they just require bleeding/servicing?

Many thanks

 

[willin]

Sounds like you need some inhibitor in the system, its a cheap fix to try first.

 

[Gwyn1]

Hi Willin, Thank you for your advice. As I have a Combi Boiler, how difficult would it be to add an inhibitor to the system ?. Would the whole system have to be drained and flushed, or could it be done via a radiator ?

 

[MH]

Isolate one rad, and drain that one.
Another issue could be they system needs balancing. On the noisy rad, tweak back the lock shield on the other side by half.

When did the problem start?

 

[Gwyn1]

First noticed it about Nov last year (thought it was a diesel engine running outside the house . Have closed the other side taps by half a turn on the affected rads, so will see if that cures the problem. many thanks for your suggestion

 

[willin]

As MH says add by radiator let it run around the system for a day or so then try balancing if not.

 

[silverdale]

I have a magnetic filter With isolater valves. I simply turn the combi off, let it cool, turn off the water, drain out the water in the filter. Take the top off the filter then fill it back up with inhib. Reopen the filter values, kick the combi back up then run it on hot for an hour jobs done.
Make sure you bleed all the rads starting at the bottom and don't over pressure the system. 1.2 - 1.5 is normally enough.

 

[IANB]

At least the clown bit of user name is apt