Intergas Eco RF 30, Evohome and Opentherm

[fergie_]

Hi there, I have been lurking for a while and thought it was time I joined:

My current system is aprox 10 years old in an S plan with heat only (dying) boiler and large unvented tank.

I've just invested in Evohome and currently running it in standalone mode (I didn't know it could do this either) with the unit controlling the HR92s only.

The plan is to Install the Intergas Eco RF 30 and run it in either heat only or system mode. Combi is not an option.

I have an open therm bridge on order along with the hotwater kit. The current controllers and 2 way valves are siemens / honeywell.

I'm planning to create aprox 11 zones via the HR92s. Will the Eco RF and the Evohome be able to get along or am I asking for trouble? I understand at the moment weather compensation isn't an option I can add to the mix.

If not the Eco RF, are there any better options? Ideally I'm looking for a boiler that is going to be future proof and last a decade or two...

Thanks.

 

[Dan Robinson]

The boiler will work fine, but the OpenTherm is not happy with multiple zones. It works perfectly with weather compensation. I have this exact set up at home.

 

[fergie_]

So I'd be better off ditching the opentherm (one of the reasons for choosing this boiler) and using weather compensation instead?

I'd read some people had had problems, but no solution found yet?

 

[Dan Robinson]

No solutions yet unfortunately.

But look at it this way. You'll save yourself £50 in hardware and get the same end result.

 

[fergie_]

Maybe I've been listening to the evohome sales people too much - opentherm, opentherm, opentherm - nothing else lol.

But, yes weather compensation would be ok if thats the route I need to go.

 

[Dan Robinson]

Maybe I've been listening to the evohome sales people too much - opentherm, opentherm, opentherm - nothing else lol.

The joys of sales people.

It will work, but it won't modulate the flow temperature.

 

[fergie_]

Are there any heat / system boilers which will work correctly with opentherm and multizoned evohome?

I will be installing the water kit as well.

Ideally I want the setup to be reliable and efficient as possible, but the main purpose is to be able to control each room seperately.

 

[Dan Robinson]

I've been told that the Viessmann 100 and the ideal vague will, but frankly the Eco RF with weather compensation in system trim will be just as efficient and better /equal warranty.

Especially with hot water priority.

 

[fergie_]

I can't help thinking the whole point of being efficient as possible is to be able to use opentherm to control the modulation.

Surely relying on temp adjustment would be a step backward?

Makes me wonder if the RF is the right boiler? Which is a real pity as on paper it ticks all the boxes.

 

[Dan Robinson]

OpenTherm modulation and weather compensation modulation achieve the same thing from different ends of the scale.

One is internal reference the other external reference. With room level control you can set one the weather compensation can fine tune things more than you can with OpenTherm, but it assumes a correctly sized emitter for the room.

It's a bit of a pain because we're not sure what the problem is. In theory the fault is in Evohome... OpenTherm spec dictates on the face of it, that the thermostat is the controller and the boiler a slave.

However my Evohome and OpenTherm bridge worked fine on a Strebel boiler I had fitted previously.

Now, my Intergas Eco RF sits in Heating mode at whatever the setpoint limit is in the boiler software which indicates there is more of a two way street.

Hence, until I can get more information from either Honeywell or Intergas, I'm back to weather compensation.

Which, as my emmitters were correctly sized, follows the modulation curve perfectly with the heat output and targets for the rooms.

 

[fergie_]

What do you mean by room size emitter?

It does make more sense though in what you are saying.

I'm lucky that I have found an installer who is happy to install whatever boiler I settle on. He is also keen to learn about evohome.

I can run in either system or heat only mode, but combi isn't an option due to our water demands.

 

[Dan Robinson]

Emmitters are the rads or underfloor heating.

 

[muggles]

You'll be running in system mode...the hot water priority feature on Intergas is great

 

[fergie_]

Emmitters are the rads or underfloor heating.

Haha, I had taken it as a signal emmiter - now that would be clever if the boiler knew the size and temp of each room.

Now if only it was possible to like opentherm and temp compensation...

My current set up is heat only in S plan with pump in the airing cupboard next to the unvented storage tank. It's easy enough to keep it that way or convert to system using an internal pump.

 

[ChrisZx]

Hence, until I can get more information from either Honeywell or Intergas, I'm back to weather compensation

Did you ever get it to work? Was thinking about installing ECO RF and Evohome via OpenTherm until I read this