Plinth heater & Evohome

[Chester]

Afternoon all,

After going open plan where there once was a wall in a separate kitchen with a radiator, I now have a hydronic plinth heater(Smith's SS3). There are 2 other radiators in the room, and an arch (no door) leading from the hallway into the kitchen. All of the radiators have HR92s.

The question is would you advise fitting an HR92 to the plinth heater, or use it as a heat dump?

Thanks in advance...

[bruce_miranda]

My plumber had told me that plinth heaters don't like to be isolated. They expect water to be flowing through them all the time. I don't know if he was right or not. He also said that the electric fan was triggered by flow rates through the heater, so if you wound things down too far, the fan may think the boiler pump has shut down and turn itself off.

[Chester]

I'm sure plinth heaters don't mind how they are supplied with hot water from central heating systems, as long as it's sufficient. It's probably not a good idea to trickle water through them, they'd either never turn on (never seeing any real flow temperature), or they'd be much less effective at warming up large spaces, I believe.

They don't run all the time, just whilst there is a flow temperature inside triggered by heat demand. In my case I've decided to connect without a TRV but not opened both isolating valves all the way so flow is slightly restricted, and so far it's working a treat. It does mean that whichever zone demands heat, the plinth heater will supply also, but it's such a big volume of space compared to other zones that this doesn't seem to matter, and the rest of Evohome is compensating very well. That and the house feels so much warmer even though I've turned down the temperatures in the main zone and hallway! The plinth heater is easily isolated if needs be.

So I concur with your plumber Bruce and would recommend this approach in similar circumstances.

Cheers

[top brake]

Afternoon all,

After going open plan where there once was a wall in a separate kitchen with a radiator, I now have a hydronic plinth heater(Smith's SS3). There are 2 other radiators in the room, and an arch (no door) leading from the hallway into the kitchen. All of the radiators have HR92s.

The question is would you advise fitting an HR92 to the plinth heater, or use it as a heat dump?

Thanks in advance...

these can easily be integrated into evohome with a wireless sensor and BDR91 on a zone valve application

[morfsta]

these can easily be integrated into evohome with a wireless sensor and BDR91 on a zone valve application

We are having a new kitchen fitted and I am just about to change one of my radiators to a Smith's SS3 too. I was considering just fitting a HR92 to it till I came across this thread. If we were to fit a BDR91 and wireless sensor and just control the power on and off wouldn't the hot water circulate through the hydronic plinth heater at all times when any other zone is calling for heat? Given it wouldn't be blowing any of the heat out if that zone was up to temperature are you just considering this to be negligible then?

Why would the BDR91 be a better solution than a HR92 (with wireless sensor) as the SS3 only turns the fan on when there's hot water circulating through it?

[Chester]

I'm also interested why this is considered a viable solution. Richard at Evohome suggested the HR92 method, which still gives you the opportunity to blow cold air when you wish.

[morfsta]

I'm also interested why this is considered a viable solution. Richard at Evohome suggested the HR92 method, which still gives you the opportunity to blow cold air when you wish.

I am going to put it on a HR92 to start with and see how it goes - though we are moving into spring/summer not an ideal time to be testing! If that doesn't work too well I will simply remove it from the valve body and run the mains connection through a wireless relay instead.

I will report back on my findings...

[Chester]

I think you'll still need a room stat. The HR92 will be behind the plinth so not measuring anything like room temps. As for Spring, it's still very cold outside at the moment with regular frost and it was 4degC on the way to work this morning!

[morfsta]

I think you'll still need a room stat. The HR92 will be behind the plinth so not measuring anything like room temps. As for Spring, it's still very cold outside at the moment with regular frost and it was 4degC on the way to work this morning!

I am going to use a remote Honeywell Round thermostat (T87RF).