Best TRV's?

Discussion in 'Plumbers' Talk' started by Wizard, Mar 29, 2020.

  1. Wizard

    Wizard Member

    I'm going to replace all my old radiator valves with TRV's and wondered which people would recommend?

    Also, are the electronic valves any good? Thanks.
     
    Last edited: Mar 29, 2020
  2. MGW

    MGW Screwfix Select

    I love my electronic TRV heads, and with electronic heads any old TRV will do the job in most cases, however I have only used two types, the Eqvia eQ-3 and the Energenie MiHome, so heads cost £10 to £80 so question is if the boiler is modulating or not, and if Opentherm or not if modulating type, and will you in the future want to fit smart controls?
     
  3. The Teach

    The Teach Screwfix Select

    Danfoss 'revolver' trv's are very good but not so adaptable for all etrv heads.

    Honeywell VT117 trv's are good and honevwell etrv heads are a direct replacement for the existing head.Other etrv heads are also compatible ish.
     
  4. Joe the Plumber

    Joe the Plumber Screwfix Select

    I have no TRVs and wouldn't dream of fitting them, regardless of their perceived benefits. They're just something else to go wrong.
     
    Heat and timotay like this.
  5. MGW

    MGW Screwfix Select

    This is the adaptor guide for Energenie TRV heads it shows how to fit the electronic head to existing TRV's and in essence shows you which can be converted to electronic.

    I am not recommending Energenie TRV heads, the default eco and comfort settings can't be altered from 16°C and 21°C and it only hold the 21°C for a set time, so although it can be programmed with a smart phone, tablet or PC to do all sorts, including geofencing, and it has two sensors one for air and one for liquid so compensates for heat from radiator it does not link as it says with Nest, it does link but not as it says it should, it does not have window open detection, and to be frank the much cheaper Eqiva eQ-3 with no internet or linking to wall thermostat do a better job.

    The TRV came into its own when the condensating boiler came out, for the condensating boiler to work the return water needs to be below a set temperature, and the boiler turns down output (modulates) to keep the return water below the set temperature, and if the output can't go any lower starts to cycle off/on. To get this to work well the TRV's direct the hot water to the cool rooms and away from warm rooms until the by-pass valve lifts, so the return water is reflective of the heat required by the home. But more important they don't turn the boiler off/on but are analogue devices which will turn boiler up/down so removing the hysteresis associated with off/on controls and allowing each room independent control. The main point is with a modulating boiler if turned off with a programmer or digital (off/on) thermostat on switching back on it starts up at max output, and at max output the latent heat is often not collected by boiler. There are analogue wall thermostat that connect to ebus often using OpenTherm, but with a digital wall thermostat the less it switches off the better.

    Unfortunately there is a flaw with control using the return water, the boiler can only work out if required by firing up and circulating the water, so to stop it doing that when not required, we use the wall thermostat.

    So most of the TRV bases are the same, there are a few minor differences for example one has the lock shield valve built into the TRV, and the pressure required to push the pin down does vary, and some weak TRV heads can't push down some pins, but I have no idea which are which. Early ones were one direction only, most later ones are bi-directional so they can be mounted so you can easy reach controls.

    The heads however have many versions, wax or liquid or some early ones I think had a bellows, then electronic, for electronic the terrier i30 and the Eqiva eQ-3 are stand alone although the eQ-3 does have a bluetooth version that can be linked so if two radiators in one room they will work together, most of the rest are designed in some way to link to internet or a hub or wall thermostat that in turn connects to the internet, the problem is to stop the hysteresis and so over shooting they tend to slow down for last couple of degrees, the Drayton Wiser claims their heads are smart heads and work out when to turn down so increasing the speed that a room heats up to target temperature, not a clue if it works, EvoHome was one of the first electronic heads, and the wall thermostat is more of a hub, that collects and processes the info sent from the heads and relays it to the boiler.

    Hive is an odd one out, the TRV head sends the wall thermostat a "demand for heat" keeping the thermostat switched on even if the room it is in is warm enough, most the better quality wall thermostats have a TRV head designed to work with it, odd one out is Nest which withdrew their support for Energenie.

    However my cheap eQ-3 (£15 each) heads I have found work well, set a TRV to same schedule as the wall thermostat and there is no real reason to link them, and for geofencing and occupancy detections really all the wall thermostat does is turn boiler off, so no need to alter TRV heads as if boiler is off they can't do a thing. I feel I wasted money on the Energenie TRV head, in the main the cheap eQ-3 works better. However in summer I do check room temperature with phone using the Energenie head and then switch on a Energenie socket if required to run air conditioning unit, and I am sure I could using IFTTT automate it.

    As to being some thing else to go wrong, yes our first house had hot air central heating, no water to leak, air circulated around whole house so one thermostat controlled whole house, seemed very simple and very little to go wrong, but it kept breaking down never the less. And very expensive to run. I expect @Joe the Plumber still uses lead pipes, otherwise he would not be a Plumber, some people never progress.
     
    Last edited: Mar 30, 2020
  6. Wizard

    Wizard Member

    Thanks everyone, I have some reading to do.
     
  7. Joe the Plumber

    Joe the Plumber Screwfix Select

    I won't touch lead pipes, but I don't have much time for a number of modern plumbing fittings, including, but not limited to, TRVs, push button operated cisterns, concealed cisterns, back to wall toilet pans, plastic pipework, single lever taps, ceramic disc valves, two part full turn tap valves (ie any where the handle doesn't move up and down with the washer), close coupled loos, baths with the taps on the back wall and designer radiators.

    I think that's enough to be going on with....
     
    Heat likes this.
  8. CGN

    CGN Screwfix Select

    Big Mac and fries please.
     

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