HW demand doesn't run Intergas boiler at 100%

[chrisru]

The system is an Intergas HRE 18 SB set up using Opentherm and wired as X Plan with a single BDR91 controlling the NO (CH) and NC (HW) valves. When the CH demand is there then the system runs fine, the boiler kicks in and runs at the required level for the CH demand, when temperature is reached then it will shut itself off showing status of 1 on the Intergas boiler (required temperature reached). However when HW is selected then the boiler will run for only a few minutes before showing status 1 (required temperature reached).
I've changed the Stored Hot Water parameters to have a target hot water temperature of 60C so that even with the differential at 10C there should still demand (currently the HW cylinder sensor shows 44C). The X Plan is working fine, the valve opens to allow the water to circulate for HW and closes for CH but the boiler doesn't run flat out as I would expect and is only heating the cylinder very, very slowly with the boiler cycling a lot and off most of the time.
The Intergas boiler was working fine before being controlled by a hall thermostat with the HW performing as expected.
Any suggestions of things to try to get to the bottom of this?

Chris

[Richard]

HI Chris,

Priority Domestic Hot Water (PDHW) using X Plan is seemingly simple, but overall it is a complex setup (hence I run courses on its installation and setup at Intergas HQ).

My initial questions would be... What cylinder have you used and what is its coil rating? If it has a small coil (3kW for instance), this will be the reason for the boiler cycling and the boiler running on 1 which really won't help you.

I personally would have done it slightly differently and used Intergas' own cylinder sensor to then allow the boiler to have a dual output for heating and hot water (what we call 'Pin 5' operation), but this still requires the cylinder to have a sufficiently sized coil to allow that cylinder recovery to be achieved as quickly as possible.

I hope that helps?

[chrisru]

Yes thanks, the X Plan document was excellent, is there a similar one for the Pin 5 setup?
Looking at the cylinder it's from RM Cylinders and is a 900mm by 450mm cylinder, their closest current range have between a 10kw and 12kw coil they say.
https://www.jouleuk.co.uk/knowledge-cen ... 20Indirect

I'll do some more testing now the system has settled somewhat.

Chris

[Richard]

Yes thanks, the X Plan document was excellent, is there a similar one for the Pin 5 setup?
Looking at the cylinder it's from RM Cylinders and is a 900mm by 450mm cylinder, their closest current range have between a 10kw and 12kw coil they say.
https://www.jouleuk.co.uk/knowledge-cen ... 20Indirect

I'll do some more testing now the system has settled somewhat.

Chris

I do have a document yes, but I don't normally hand it out without the paid training I provide. Unfortunately, the questions and support it requires is beyond the support I would be willing to give as part of a normal online sale.

[Luddite]

So, OOI, who would/could/should have provided chrisru with the support that he needed?

And on what basis?

Does

the questions and support it requires is beyond the support I would be willing to give as part of a normal online sale.

imply that people who buy Evohome products online from the Evohome shop cannot get support?

[Richard]

Problem is, there is lots of information on the forums but this system integration is specialised and time consuming. Intergas do have their own technical support line. If they are unable to provide adequate support, then a local installer who has the integration knowledge of the boiler and systems should be used (we can recommend installers). Going beyond the evohome system into boiler setup and schematics has a value beyond the price paid for the components on our website. If you want to pay me the same rates as a local heating installer, then I am happy to assist.