Glow worm Ultracom cxi30 & Honeywell thermostat DT90E

[Redshock]

Looking on some advice for my parents if the boiler and thermostat are wired up correctly?

The boiler and thermostat were both installed around 2012 and I'm not sure if the thermostat has ever worked correctly. Any time my parents have wanted to increase the temperature in the house they've always gone to the boiler and pressed the advance button on the front to switch the boiler on for heat for the radiators as no matter what temperature is selected on the thermostat the boiler never fires up. I can hear the click in the thermostat when increasing the temperature, also I've replaced the batteries just in case.

I've attached a diagram of the current wiring set-up and a couple of pictures of the wiring in the boiler and thermostat for reference.

Thanks

 

[Mister Banks]

Before you turn anything back on you need to sort out that terrible wiring

 

[CBW]

It should work, as it's only a switch (wired up different terminals). Can you post photos of the boiler front and thermostat? Agree with @Mister Banks - wiring needs tidying.

 

[ericmark]

Clearly wired by a cowboy as the cable clamps are not gripping cable, this will not stop it working, but rings alarm bells.

So it says ebus and unused terminals say opentherm which is confusing me as opentherm is a type of ebus, so I would start by down loading the manual for the boiler.

The boiler can likely be turned up/down or on/off, the up/down option is the best, but the thermostat is on/off.

I am an electrician not a heating and ventilation guy, so can only talk in general terms.

Back in the late 80's gas boilers started to gain the latent heat from the flue gases, to do this the boiler needs to modulate (turn down) originally it done by using TRV's (thermostatic radiator valves) and the boiler monitors the return water temperature, however that method means boiler never turns fully off, so we started to use wall thermostats that turn up/down instead of on/off or/and using thermostats/hubs which link to the TRV heads.

Honeywell EvoHome was one of the first, but today we have Drayton Wiser, Tado, and many others which have either add on units or built in OpenTherm options. There are some odd ones, Hive is only on/off, but as long as under 22ºC the Hive TRV heads will send a demand for heat to thermostat and cause it to keep boiler running. Nest has built in OpenTherm but does not connect to TRV heads, EPH does master and slave thermostats using OpenTherm designed for when using hard wired motorised zone valves.

As to if this all makes it better I really don't know, since I have oil which does not modulate. But today the TRV seems to be king, the wall thermostat only stops the boiler cycling once all rooms satisfied.

A heating and ventilation engineer, as the name engineer suggests, trains to above level 3, i.e. higher education or degree, and expect to be paid for their expertise. I am an engineer, but electrical and electronic, so I have not got the skills required to work out best options.

Working and working well are not the same, but as to if worth paying out for an expert not sure.

 

[ianmcd]

Oh dear, what an absolute mess, the wiring is terrible.

The DT90 is simply a thermostat, in order for it to work the boilers internal control must be set to CH ON, if you actually paid somone to install that mess do not get them back, and switch the boiler on and off manually on the boiler control panel, the thermostat can not over ride the boiler timer it needs to be set to on
Edited

 

[CBW]

Oh dear, what an absolute mess, the wiring is terrible and completely wrong, that thermostat can not be connected to the ebus connection.

The DT90 is simply a thermostat, in order for it to work the boilers internal control must be set to CH ON, if you actually paid somone to install that mess do not get them back, in the meantime disconnect the two wires in the ebus connectors and switch the boiler on and off manually on the boiler control panel

I did wonder about that, but wasn’t entirely sure, as they’re seems to be another terminal for ebus, so thought it was just 24v.

 

[ericmark]

I did wonder about that, but wasn’t entirely sure, as they’re seems to be another terminal for ebus, so thought it was just 24v.

That was also my thoughts, which was why I said look at manual for that boiler.

 

[ianmcd]

I did wonder about that, but wasn’t entirely sure, as they’re seems to be another terminal for ebus, so thought it was just 24v.

I stand corrected, it can be installed like that, after looking again I can see that the OT wire is not used. I will edit my origional post

 

[Redshock]

Thanks for the replies guys. food for thought, I'll have a read up in the manual. It was installed by a work colleague of my stepdads where he was working at the time. I've tidied up the wiring and clamped everything properly. I've uploaded a image of the boiler.

 

[CBW]

Providing the temperature is high enough on the front, could be the thermostat that’s failed. If you join the blue and brown wires together, does the boiler fire up?

 

[Redshock]

I'll give that a go next time at my parents house. I'll also try disabling the internal timer and see if the thermostat does anything then.

 

[ianmcd]

I'll give that a go next time at my parents house. I'll also try disabling the internal timer and see if the thermostat does anything then.

It wont, the thermostat can not tell the boiler to come on if the timer is set to off

 

[Redshock]

Thanks I wasn't aware of that. It's probably best I get them to invest in a better quality thermostat

 

[ianmcd]

Thanks I wasn't aware of that. It's probably best I get them to invest in a better quality thermostat

its not the qualty of the thermostat, that is how it works, its a thermostat, leave the boiler timer set to constantly on and switch the boiler on and off with the thermostat

 

[Redshock]

A small follow up. Taking ianmcd advice putting the boiler on constant the thermostat works perfectly. If I switch back to the boilers internal 24 hour timer the thermostat doesn't appear to be able to override the internal timer.