Ideal Logic System 24 with Weather Compensation and OpenTherm

[Jahill]

I'm completely new to the world of OpenTherm, so please be gentle!

I'm trying to figure out whether OpenTherm will work with the weather compensation on our Ideal Logic System 24s.

We've just switched our heating to the Honeywell Evohome using their OpenTherm bridge. While this part of the system is working well, I was hoping the Weather compensation would set a limit on how high the EvoHome can request the set point, however it looks like the set temp goes to 84c.

This might be a fault with the boiler as their outdoor weather compensation kit without opentherm also selects a set point of 84c, but this might not be worth fixing if Ideal’s weather compensation can’t work with opentherm anyway.

[wardl895]

I know im digging up an old thread, however i have also found this question/post by the powers of google, i have still not found out if the ideal boiler will use the Opentherm AND The weather compensation device together? I would like to think the boiler if asked for heat from Opentherm will startup but alter itself dependant on outside conditions?

[Jahill]

I know im digging up an old thread, however i have also found this question/post by the powers of google, i have still not found out if the ideal boiler will use the Opentherm AND The weather compensation device together? I would like to think the boiler if asked for heat from Opentherm will startup but alter itself dependant on outside conditions?

That was my thinking too, but when using OpenTherm, the boiler only runs warm enough to offset the heat being lost by the building, which is itself dependant on outside conditions. The only time it doesn't seems to be if: a) it's heating the hot water; or b) the temperature in one or more of the rooms is 2ºc lower than that room's set temp. Our system seems to tick over during the Autumn at with the boiler running at 35ºc, increasing to around 42ºc in the winter. I could never get weather compensation to work full stop with our Ideal boiler - I tried two different sensors and they both sent the boiler up to its maximum point even in mild weather.

I love the OpenTherm system, the temperature inside the house stays absolutely constant. One thing I like less is that the minimum output of our boiler is higher than the amount required to keep the house at a steady temp which means the boiler has to cycle. This wouldn't be an issue, but the resultant smell of gas in the garden suggests there is some wastage involved here.

[Jahill]

BTW I also had the system valves for the radiators changed to the 'normally open' type and electrically wired to the hot water circuit. This way, when the boiler is heating the hot water, the radiators don't suddenly go from 35ºc to 70ºc. This would send the room temperature skywards until the thermostatic radiator valves noticed and they would then start shutting the water to the radiators off (and the same in reverse as the rooms subsequently cooled down).

It also cuts the noise to a minimum from the radiator valves (we hardly hear them now as they rarely need to adjust).