Cost of upgrading 9 radiators to trvs, plus a bit of pipe work?

chubsta

Just looking for a rough guide, have 9 radiators - all have the old style twisty knobs to control flow and want to upgrade them all to trv valves.

5 of them have a standard sized pipe going in at opposite ends, 4 have this weird thing where the valve at one end has two micro bore pipes going in and there is no outlet at the other, I’m guessing these ones would need to pipework extending to the other end of the radiator to make them ‘standard’.

for simplicities sake I would prefer the plumber to supply everything.

before I get all excited about having posh new valves on my old radiators, and so I don’t waste anyone’s time in getting quotes for something I could never afford, I would prefer to have at least a vague idea of potential cost.

although trvs are cheap in themselves, I am pretty sensible and know the cost will be made up of not only the parts but also labour time, and everything else a plumber has to build in in order to make a liveable profit!

FreeBear

Some photos of these "weird" valves would help.

Before you commit to TRVs all round, a couple of points to bear in mind. The radiator closest to your thermostat (traditionally in the hallway) should not have a TRV fitted. The reason being, if the TRV shuts down before the room is up to temperature, the thermostat will continue to call for heat.

At least one radiator should be left without a TRV to act as a bypass so that when all the other TRVs operate, the central heating pump can still push water round the system - If it can't, then there is a chance that the pump motor could burn out. The alternative is to have an automatic bypass valve.

If you have a boiler capable of modulating its output coupled with a smarter thermostat, you may find that the boiler starts to short cycle when some of the TRVs operate - I have a Viessmann 050 that can modulate down to 3,2kW, and it quite often runs at around that point. Should a TRV or two operate on the bigger radiators, my boiler short cycles which kills efficiency. Consequently, I leave all the TRVs on max.

chubsta

Thanks for the quick reply - above is what the odd ones look like!

So I would need 8 instead of 9 then - cheaper! - the thermostat is a Hive one in the hallway so Im guessing the hallway rad would be the best to leave trv-less?

FreeBear

chubsta said:

Thanks for the quick reply - above is what the odd ones look like!

So I would need 8 instead of 9 then - cheaper! - the thermostat is a Hive one in the hallway so Im guessing the hallway rad would be the best to leave trv-less?

From a quick internet search, that appears to be a Maxitwin valve - You can get TRVs to replace it for £50-120 each. But not sure you would have enough space between radiator & valve. A conventional TRV can be had for less than £10 from somewhere like Screwfix or BES. Extending the pipe to run along just above the skirting wouldn't be very difficult, and as long as copper pipe & solder fittings are used, should look fairly neat.

You have a pretty old radiator there, so whilst the system is drained down and pipework being adjusted, it would be a opportune time to fit a bigger radiator. I replaced some of the old Type 10 (single panel, no fins) here with T11 and T21 radiators - They don't look much larger than the old T10, but kick out quite a bit more heat. As a result, I can run at a lower flow temperature for better efficiency.

Rough ballpark cost for labour would be around £50 per radiator. Perhaps less if you have all bar one done. You'll probably want the system balanced afterwards, which can be time consuming, although not difficult to do if you wanted to give it a go.

Oh, and don't forget to have corrosion inhibitor added when the system is refilled.

chubsta

Also, my logic behind replacing the existing valves is that they are all very old and some are nigh on impossible to actually turn, others have broken knobs etc, so I would really be doing it for a bit of control but mainly aesthetics so can see myself leaving them in full most of the time. But if I am going to replace the valves I may as well go the trv route instead of trying to replace like for like.