Intergas, Opentherm & Weather Compensation / Outdoor Temperature Sensor

[jc001]

I have an Intergas HRE36/30 set up a a combi. Its coming up to 10yrs old. I have the Intergas outdoor temp sensor/weather compensation (WC) and have just upgraded my controls to Tado, connected to the boiler via Opentherm (OT). Original controls were actually OT too (Rhemea).

It has come to my attention via this form that the Intergas is best set up using OT or WC, not both, although despite trawling the instructions I cannot see anything advising against both OT and WC.

Which one (or both) should I leave connected and why?

Thanks in advance.

 

[Swwils]

The WC will be superior since it's an actual measurement of local weather and thus the load required.

The tado OT is at best rough geolocated data and it uses "assumed" radiator flow temps in its calculations as far as I am aware.

In any case intercaste support very little of open therm, which is not unexpected because hardly anyone does.

You will need to be vary careful if you have also got tado smart radiator thermostats, using them for room to room control can quite easily be NOT the correct thing to do.

 

[jc001]

You will need to be vary careful if you have also got tado smart radiator thermostats, using them for room to room control can quite easily be NOT the correct thing to do.

I don't have them, only really wanted the ability to turn the heating on/off remotely; this is the only area where I could see any quantifiable gas savings.

Why would using the tado rad thermostats be the wrong thing to do?

 

[muggles]

Generally OT is preferred over WC on Intergas. I can't think of any specific reason why you shouldn't use both together, maybe @Razor900 will have an idea

 

[Razor900]

The WC will be superior since it's an actual measurement of local weather and thus the load required.

The tado OT is at best rough geolocated data and it uses "assumed" radiator flow temps in its calculations as far as I am aware.

In any case intercaste support very little of open therm, which is not unexpected because hardly anyone does.

You will need to be vary careful if you have also got tado smart radiator thermostats, using them for room to room control can quite easily be NOT the correct thing to do.

Mmmm wrong on most counts where Intergas are concerned.

The WC on the HRE range is a very simple curve and generally would lead to long warm up times from cold. It is very far from a modern version

Intergas support OT extremely well - They should do, some of the boards are made by Honeywell the company that developed OT in the first place.

Amongst others Vokera implement OT very well @vulcancontinental

OP there is no problem leaving OT and WC connected but although the boiler will record it the outside temp will play no part in the flow setting process it will defer to the Opentherm controller.

BTW I presume the old controller was an Isense? Good units, far ahead of their time for domestic.

 

[jc001]

OP there is no problem leaving OT and WC connected but although the boiler will record it the outside temp will play no part in the flow setting process it will defer to the Opentherm controller.

BTW I presume the old controller was an Isense? Good units, far ahead of their time for domestic.

Thanks - Ill leave the OT and WC connected and boiler will use OT.

Yes an isense - I bought it because of the OT compatibility. Build quality was terrible however, very 'plasticky' and the dial had a mind of its own!

 

[Swwils]

(dupe)

 

[Swwils]

Having the WC although just a simple curve measure actual temperature is important.

the boiler will record it the outside temp will play no part in the flow setting process it will defer to the Opentherm controller

This is in effect the issue, the tado is really granular. If you have underfloor heating the assumed temp of the room output is also totally wrong in OT with tado.

Why would using the tado rad thermostats be the wrong thing to do?

They can be great, but they can also mean people turn of heat emmitters in rooms that are part of the thermal envelope of the home - so you just get heat transfer through internal walls to this now cold room - this effectively reduces the surface area available to your heating system which leads to decreased efficiency.

It is more than likely to should not be turning off the heating, set a comfortable temperature and good fall back temperature and rely on the WC but do not fully turn off the heating.

Unless your house is absolutely massive that boiler is comically oversized because you'll be load compensating to 7kw anyway.

 

[Razor900]

Having the WC although just a simple curve measure actual temperature is important.





Unless your house is absolutely massive that boiler is comically oversized because you'll be load compensating to 7kw anyway.

When the outside temperature is around 5 degrees the built in weather comp will set a flow temp of less than 50 which is probably not enough for an older less efficient house in the UK. It may eventually get up to temp but warm up will take a very long time.

Even the Intergas UK technical helpline doesn't have a clue how to set it up

With OT the boiler will run at the maximum flow temp set until it reaches the control band where it will start to modulate flow temp so the property will reheat much quicker before the rads go into 'cruise control' mode.

If you are talking about something like the Veissmann implementation of WC that is a very different beast altogether and far more sophisticated.

The reason for a 36kW boiler is that it's a combi. The heating side should certainly be range rated down to suit the house load. The minimum OT temp will probably need adjusting as well or the system will tend to sit about a degree under set point and never turn off.

As with all controls including WC the setup is as important as the components. I think that's something we can all agree on...

 

[jc001]

The heating side should certainly be range rated down to suit the house load. The minimum OT temp will probably need adjusting as well or the system will tend to sit about a degree under set point and never turn off.

Thank for this - have just done some fag-packet calcs and range rated the 'maximum CH power' to 38%, which equates to approx. 12.5kw. All my rads total about 11kw.

Any tips on what or how to set minimum OT temperature to? 30yr old house, well insulated, all rads. Factory default for HRE 36/30 is 40deg

 

[tech749]

When the outside temperature is around 5 degrees the built in weather comp will set a flow temp of less than 50 which is probably not enough for an older less efficient house in the UK. It may eventually get up to temp but warm up will take a very long time.

Even the Intergas UK technical helpline doesn't have a clue how to set it up

With OT the boiler will run at the maximum flow temp set until it reaches the control band where it will start to modulate flow temp so the property will reheat much quicker before the rads go into 'cruise control' mode.

If you are talking about something like the Veissmann implementation of WC that is a very different beast altogether and far more sophisticated.

The reason for a 36kW boiler is that it's a combi. The heating side should certainly be range rated down to suit the house load. The minimum OT temp will probably need adjusting as well or the system will tend to sit about a degree under set point and never turn off.

As with all controls including WC the setup is as important as the components. I think that's something we can all agree on...

Hi Razor900
Wonder if you can advise at all, I've had a Viessmann 050 25kw combi boiler with Weather Comp installed to replace my old hot water tank system. The installer has fitted an EPH CP4 RF thermostat and receiver connected to Open Therm, and says that they work together to control the flow temperature according to the room temp and outside temp. I thought they might clash, as Open Therm will effectively control the boiler as far as I can tell, but I may be totally wrong here.

I'm struggling to understand how that can work, I have voiced my concerns to the installer who is very knowledgeable and a Viessmann registered installer, and he is looking into it. I just wanted to get my head around the system first, in case I have any questions, and be able to understand the answers. Any help appreciated. Thanks.

 

[monkeysballs]

i have a 200-w using no external controls and its been working better than my old opentherm evohome setup on my vaillant
but im still in my first year with it. even with the old setup i found it better to heat the entire house than micro zone.

 

[monkeysballs]

i have trv's just dumb ones (the heads arnt attached at the moment) to limit maximum temp the room will get up to. im still trying to dial in the flow through my radiators and my curves (only got the boiler in march) in theory if rads are sized correctly then you dont need trv's as the rad will only emmit the right amount of energy to get the temp you want then maintain it

 

[monkeysballs]

im running .6 slope and level 5 thats a flow of 35c at 0c and 29c at +10

but its not been really cold so far when i have had it so will see what this winter holds.

 

[monkeysballs]

if your wanting to actually restrict the outputs of rads propperly then you will need decent valves as low flow temps require very small amounts of water to flow per minute and honestly most valves you cant limit as they are not accurate enough and are designed for high flow hi temp systems