radiator keeps making a tapping and knocking noise

hello

im a very inexperienced idiot so please be patient with me.

i have 2 new radiators, that due to a misordering were installed 3 months before it had a thermostat fitted. they both worked perfectly.

they have recently had the thermostats fitted. one is absolutely fine, while the second, although working fine, continually makes an irritating tapping/knocking noise. its not too loud, but loud enough to become very irritating.

we had this probvlem once before on a different rad in a different room. the plumber who fitted these new rads managed to sort that one ouit very quickly while he was here. unfortunately, i was out of the house when he did it so have no idea what he did.

if anyone can help, please get back.

thanks in advance

del

trv is on the return instead of the flow or visa versa

Most TRVs are bidirectional and it doesn't matter whether they are fitted with the head horiz or vertically or whether on flow or return. Some aren't however and if fitted the wrong way can be noisy.

Feel the two pipes at the ends of rad and identify the flow which should be noticeably hotter. Then check if there are arrows on the TRV body and make sure if they point in one direction only that they are correctly showing the flow into or out of the radiator.

Other possibilities include expansion of pipes under floor rubbing against timber joists. notches too tight (Usually a clicking/ticking noise) or poorly secured pipes knocking together.

Other possibilities include expansion of pipes under floor rubbing against timber joists. notches too tight (Usually a clicking/ticking noise) or poorly secured pipes knocking together.[/quote]

hmm. already sounds too tricky for me. thanks anyway. i guess its a call to the plumber tomorrow

one quick thing, what do you mean by 'notches too tight.? that clicking/ticking sound you describe is a pretty accurate description

thanks again guys

del

When pipes are running at rightangles to joists, notches are cut into the top of the joists close to the walls to get the pipes down below flooroards. If they are not wide enough or deep enough the pipe may be in tight contact with the timber. When as pipes heat up they try to expand lengthwise but friction builds up until it is overcome and there is slight movement (noise). This cycle restraint/expansion is repeated and a similar process occurs on cooling/contraction.