TRV why do they need changing?

[ericmark]

I had a massive problem, there was a likelihood of the cistern falling through the floor, the shower tray was leaking, the beam under it had rotted away, and I managed to get a plumber and chippy who worked together to repair it.

There was also in comparison a minor problem, there was no or little control of the central heating and domestic hot water, and the plumber got all the parts required, but was to return to do central heating as that was not emergency work, plus it allowed me to prepare for it.

So I was left with two motorised valves, a by-pass valve and 14 Tower TRV2 radiator valves, so I have fitted Nest Gen 3 and two wiring centres and the motorised valves are now wired in ready.

I already had 4 MiHome Energenie TRV heads and has added a further 5 Eqva Bluetooth Sma heads, however the plumber has put his back out, so it seems it will be some time before he returns.

The original TRV Mistral 1 were mounted horizontal, and in many cases on the return, and I know from bitter experience the MiHome heads work better on the feed, also the Eqva Bluetooth Sma heads are hard to read when mounted horizontal and in some locations the radiator does not have enough room for the longer electronic heads to fit.

So may be good reason to swap the lot, however I wonder what goes wrong the TRV bases and do they really all need changing? Thinking he may not return before winter, so do I really need them all changing?

Also I was leaving the 4 TRV's in the flat with non electronic heads, flat is not used much, so what makes a good head, and what is rubbish? The new ones say liquid sensor, I want a back ground heat in the flat to stop freezing, not sure if the TRV really has much work to do down there, as wall thermostat will most of time be turned to anti-frost only.

I can't work out why mechanical TRV heads are so expensive, in some cases more expensive than electronic, to me it seems a head which can have day and night setting must be better than one where you have to physically turn it up and down day and night, and a display in deg C is better than 1 to 5.

But if it was that simple, there would be no mechanical type sold, so there must be more to it, but what?

 

[Madrab]

I thought the MiHome TRV's were just the heads and using adapters they used the valves that were already there or are to be fitted? Wouldn't matter then whether they were on flow or return then unless the valves weren't universal?

The valves themselves, like any valve, will wear with time and the seals get harder as they go through more and more heat cycles, they also can clog up a bit if the system isn't the cleanest ending up in them not closing properly. They're not really serviceable so replacing them is the best bet when they start to play up.

Some mechanical heads are wax, some are liquid. Some (liquid) are more sensitive than others and of better build and design quality giving better control and are usually more expensive. Same can be said for electronic, all depends on the quality of the components and the calibration/sensitivity determines prices.

With these components I usually find that more expensive can be better. Depends on how tight a control is needed/wanted.

 

[ericmark]

Yes MiHome is just the head, may be I did not explain, he has a box full of TRV's to change but the heads will not be used on most, the electronic head will be used. The bluetooth electronic head is £15 you can get non bluetooth for £10, they exercise valve once a week and allow a weekly schedule so night and day setting are not the same, which to my mind a great advantage.

The MiHome are more like £40 each, and are set to follow Nest, which is an advantage down stairs, all singing from same song sheet, but upstairs don't want bedroom heating in the day and at night much cooler than down stairs rooms. Each room will need its own schedule.

But since you say seals go, may as well be changed.

 

[mrStat]

Personally, when clients have/want eTRVs and need new TRVs; I supply and fit the Drayton EB valves. These are the same valve bodies that come with the TRV4, in-built balancing, replaceable seals and quite simply one of the best TRVs out there in my opinion.

For the amount you'd pay for a Tower TRV and Head, you could probably swap them for the EB's without a head and you'd be getting a far superior valve. Additionally, in my opinion, it's not leaking TRVs around our way, our biggest problem is stuck TRVs - I can guarantee we will have at least 2 calls a week for a stuck TRV in the winter time.

 

[ericmark]

Hopefully using electronic TRV's which exercise the TRV should not stick, I have not seen any report from the expensive MiHome TRV head to say either valve sluggish, valve range too wide, or too small, but the cheap eqiva does, I do wonder in hind sight if that was part of the problem in my mothers house, I blamed valve speed for some of the problems.

Clearly if the boiler is not running it does not matter how wide the valve opens the radiator will not get hot, be it mechanical or electronic the valve could end up wide open when the boiler starts, so the radiator become hot before the valve has time to close, causing a massive over shoot, with the Nest wall thermostat being linked to the TRV hopefully the boiler will fire up at same time as valve wants heat, however not run a winter with Nest yet.

Mothers house was a lot smaller than this one, yet the boiler was larger, I wonder if over size, 8 to 28 kW where this house is 18 to 25 kW. The Honeywell Y6630D was a really good thermostat, however not really suited for a modulating boiler, the thermostat used a mark/space ratio to reduce the hysteresis, however that stopped the boiler modulating correctly, so in real terms made it worse not better, I suspect the Nest does the same, but the amount an oil boiler modulates one may as well forget it.

 

[Hot&Cold]

Tower TRV2 radiator valves,

come across those re-branded items before (corgi branded ) for some reason a few vibrated both on the flow or return. So exchanged them for VT15's silence

 

[ericmark]

come across those re-branded items before (corgi branded ) for some reason a few vibrated both on the flow or return. So exchanged them for VT15's silence

Not fitted yet so don't know how good or bad, even if fitted would not be using at the moment, I remember the bangs from the old TRV's, sisters house had some wrong way around, at that time they were not bi-directional. The plumber did note flow on most of the radiators with idea all fitted to feed side. However not sure about the kitchen, the return side is next to door to outside, so would it be better fitted to return so the window open function works better?

Never had a window open function before, it says "With a rapidly reducing temperature, the radiator thermostat automatically detects that a room is being ventilated. In order to save heating costs, the temperature is then reduced for a certain period of time (15 minutes, set at factory)." It then goes on about how to set temperature and time.

As to how rapid the drop needs to be, I don't know. So big question, in kitchen should I fit on return so closer to door, or will it not matter?