Central heating issues

[Bob Stapleton]

Hi all. I've got an issue developing with my heating that is causing some head-scratching. First, some background info - the system consists of a 36kW condensing boiler, supplying 10 radiators, 2 towel rails & an underfloor loop, using 22/15mm copper tube. A magnetic filter is fitted on the return leg to the boiler. All the radiators have unbranded thermostatic valves fitted, except the underfloor loop which is, apart from a blending valve, unrestricted. The system is approx. 9 years old. The past couple of years has seen an issue developing where gurgling can be heard when opening the thermostatic valves a little more than the nominal setting. However, this only happens on certain radiators. More often than not, air can then be bled from that radiator. The radiators affected are on both the ground & first floors. The system is drained regularly each year & refilled, adding inhibitor. Last year I drained the system, removed each radiator & flushed them. At the same time, the offending valves were replaced. The problem still persists. Has anyone got any ideas of other remedies I can try? Many thanks.

 

[ShaunCorbs]

Change the trvs to danfoss ras c2

 

[king of pipes]

Is it a system boiler or heat only with a external pump? This could be a pump issue as the efficiency drops off with a ageing pump . Kop

 

[oz-plumber]

Every time you drain a system and re-fill you will have minor air issues like you are describing.

Once in a while open all the TRV's fully, let the system run for a while, shut the system off and bleed the rads.

I would do this twice a year at my house, but I'm a heating plumber with a 20 year old neglected heating system, with a boiler that won't die, radiators and radiator valves that won't leak

 

[Bob Stapleton]

Is it a system boiler or heat only with a external pump? This could be a pump issue as the efficiency drops off with a ageing pump . Kop

Hi. It's a system boiler & strangely enough the pump had to be replaced about a month ago. But the gurgling is still there.

 

[John.g]

Has the magnetic filter been cleaned and what is the boiler pressure when cold and hot?.

 

[Bob Stapleton]

Has the magnetic filter been cleaned and what is the boiler pressure when cold and hot?.

Yes, the filter is cleaned every time the system is drained, once a year. When the boiler is cold the pressure is around 1.1 - 1.2 bar; that increases by 0.1 - 0.2 bar when hot.