ASHP with WiFi TRVs

[NikoV6]

Have the Honeywell Evo home system. Interested to hear how others with an ASHP and WiFi TRVs have set up their system

[Yuff]

Have the Honeywell Evo home system. Interested to hear if others with an ASHP and WiFi TRVs have set up their system

I looked at getting wireless Trv’s but went for a system where the trv’s can use the reverse valve, on the Ashp’s, and not sure if they come with a wireless option.

[Tinbum]

I've just bought some Tp-Link Kasa wifi TVR's and they seem to be working great. Can't seem to control them with NodeRed yet but working on it.

https://ukstore.tp-link.com/products/ka ... ke100-tkit

[NikoV6]

Thanks both!

My question really is how to set the ASHP temp?

I have the TRVs set to 16 and that pretty much all year keeps them off. When we want heat I have them set at 18 which again gives heat when we want it.

I have the ASHP set the same, 16 for off and 18 when we want heat.

What seems to defeat this is when the ASHP thinks the house is 18 because the control panel (and I assume its thermostat) is in our bathroom (dont ask, old cottage, limited options!) Other rads in the house are asking for heat and will not come on as the ASHP thinks all is good!

If I set the ASHP to say 20deg all the time, will it run and try and get the bathroom up to temp even though the rad in there is set for 16 as we dont want heat?

[Countrypaul]

Since you appear to have an Ecodan ASHP, you should be able to use an external thermostat (external to the control panel) - at least we can with an FTC5.
I use W1209, but taking the temperature of the lower part of our Thermal Store.

Slightly different position to you as we have Wifi Thermostats but a wiring centre for the UFH which puts the pump on if there is a call for heat from any thermostat.

[Yuff]

I haven’t played around with anything apart from the room thermostat.
But as I have 2 heat pumps and I know from battery issues, it can cause problems, I just leave the settings to the plumber.
I would have thought though you want your room, where the thermostat is, radiator working.
I have a similar issue with our thermostat, it is near the stairs and the radiator close to it doesn’t work very well, and it barely gets warm, so all the other rads are hot but the thermostat thinks it isn’t warm so calls for heat.
I turned the thermostat down a couple of degrees to compensate.
Hopefully when the rads are fitted( they are being delivered tomorrow and the hybrid fan is expected in a couple of weeks) this issue will disappear/

[martinW]

I was under the impression that you need maximum flow rate and pretty much whole house heating to make an ashp work efficency.

If you don't have the water flow in the heating system the ashp is likely to be short cycling.

[sharpener]

I have the ASHP set the same, 16 for off and 18 when we want heat.

What seems to defeat this is when the ASHP thinks the house is 18 because the control panel (and I assume its thermostat) is in our bathroom (dont ask, old cottage, limited options!) Other rads in the house are asking for heat and will not come on as the ASHP thinks all is good!

If I set the ASHP to say 20deg all the time, will it run and try and get the bathroom up to temp even though the rad in there is set for 16 as we dont want heat?

I think you need to spoof the ASHP somehow so it responds only to a call for heat from any one of the rads. Maybe this analogy will help...

I converted our oil-fired system to Evohome a few years back. The boiler firing is controlled by a BDR91 Boiler Relay which does an OR function of the individual wireless TRV demands. I wired it in parallel with the exising room stat on the landing as that was easy to get at and within wireless range. Room stat now set to 5C as a frost override. Works fine (once I had found and replaced a faulty TRV, boy are the Honeywell diagnostics cr*p to non-existent).

The BRD91 has floating changeover contacts, so you could easily connect into a suitable point in the Ecodan control circuitry. Can you get a separate external room sensor for the Ecodan? As an extreme bodge you could then put the sensor in an enclosure with a small heater e.g. 15W light bulb arranged to turn OFF when there is a call for heat e.g. by using the normally closed contact on the BDR91.

Also found a link which says "This [generic] Wireless Relay Box will not work with a Heat Pump and instead you will need a Post-2021 BDR91T1004 with the house symbol on the front cover of the BDR91". Haven't been able to discover what the difference is.

[SafetyThird]

I have a Tado thermostat/controller for our ground source heat pump and fitted individual wifi trv's on each radiator around the house except the ones that were required to be free flow.

After a year of trying to figure out issues with the heat pump, we took them all off and put regular trv's back on. Works perfectly now. The radiators were sized for the heat demand of each room and are designed to work with full (for near full) flow, otherwise you get pressure warning alarms from the pump. Because each TRV would call for heat independently, the pump was cycling too often and also there was often only one or two TRV's open which reduced the volume of the working system leading to overpressure errors.