thermostatic return valves on rads?

Doglover88

are these purely for controlling the temp (probably a really stupid question ) Fitting new rads and valves and wondered if i still need TRV's on them? I've replaced the old boiler with a WB condensing combi with radio controlled thermostat, does this mean i no longer need TRV's on each rad?
And more importantly i can fit some nice shiny ones
glen

plumb1_2

glenbat wrote:

are these purely for controlling the temp (probably a really stupid question ) Fitting new rads and valves and wondered if i still need TRV's on them? I've replaced the old boiler with a WB condensing combi with radio controlled thermostat, does this mean i no longer need TRV's on each rad?
And more importantly i can fit some nice shiny ones
glen

The RC state will only control the room it's placed in.you would still need TRv's

cheekymole

Make sure they are put on the correct side, out of 13 my cr*p (ex) plumber fitted 6 on the wrong side which caused considerable problems

dark_star_3

cheekymole wrote:

Make sure they are put on the correct side, out of 13 my cr*p (ex) plumber fitted 6 on the wrong side which caused considerable problems

...or fit the ones that can be fitted on either the flow or return side

Doglover88

this is sounding harder than i first thought, flow and return sides? how would i determine that?

uncle_buck_3

The radiator has 2 pipes to it...the one that heats up first when the heating is put on is the flow.

Doglover88

thanks people.. common sense really i guess

moneysavingplumber

Although reversible TRVs can be placed at either end and will work, to maximise on efficiency they should be placed on the flow with the return lockshield turned down enough to give a 20 degree temperature drop between the two pipes, this way you restrict the flow out of the radiator concentrating the heat inside the rad, as opposed to restricting the flow into it. The 20 degree differential is recommended for condensing boilers, but a lesser differential may be needed for older boilers with more sensitive overheat thermostats. Every radiator except the one closest to the room thermostat should have a TRV and the system should be fitted with programmer, automatic by-pass and preferably a restrictive lockshield valve on the coil return from the cylinder set to give an acceptable temperature difference between the two again. Trust me, it sounds more complicated than it actually is, although major changes to the system should really be done by a pro and I personally wouldn't recommend the above as DIY work.

Doglover88

thanks plumber ive printed that off and will force it upon whoever does my rad for me, its just a swap over, dumping the old faded double rad for a Stelrad compact style horizontal, worked out the btu needed for my room so it should hopefully look a lot nicer

moneysavingplumber

glenbat wrote:

thanks plumber ive printed that off and will force it upon whoever does my rad for me, its just a swap over, dumping the old faded double rad for a Stelrad compact style horizontal, worked out the btu needed for my room so it should hopefully look a lot nicer

Lol, you're welcome, but tread carefully, you know how temperamental us plumbers can be, don't be surprised if he/she claims it's a load of b******s!

If it's only one rad that's being replaced, they're not necessarily obliged to do the above, but it would be worth it to get a decent plumber that knows what the efficiency guidelines are to balance your system up properly, if it's running more efficiently it's money in your pocket ultimately.

moneysavingplumber

PS: I just re-read the OP, as yours is a Worcester Condensing combi, the above bits about auto bypass (incorporated in the boiler) and cylinder coil return (non-applicable) wont apply to your system anyway, but everything else will.