Boiler Shut-Down Problem

[dk1uk]

Hi - I'm hoping that someone can help me.

I have a Vaillant Eco-Tech sealed system boiler which was installed in 2013. It runs both hot water and CH. There are three heating zones: one wired Honeywell DT90E thermostat and two wireless Honeywell DT92E thermostats. And a Honeywell programmer.

For some reason the boiler never seems to shut-down the CH when the programmer tells it to. For example, this evening, I put the CH on for 1 hour at about 6pm - the programmer switched off at 7pm, but the boiler was still heating the rads until 7.30pm when I eventually clicked the temperate down a degree on one on the thermostats - only then did the boiler shut-down. It would have shut-down eventually, it always does but I can't seem to find a pattern as to how long it normally takes but sometime it's well over an hour over the programmed time.

If I have to I'll get someone out (as I'm only a DIY'er) but keen to sort it out myself if it's simple to do so.

Many thanks.

 

[Razor900]

Does it have a bypass valve fitted to the system or just three 2 port valves?

 

[dk1uk]

Hi - I know it has the 2 port valves, but how can I tell if it has a bypass valve?

Thank you.

 

[Agile]

For some reason the boiler never seems to shut-down the CH when the programmer tells it to. For example, this evening, I put the CH on for 1 hour at about 6pm - the programmer switched off at 7pm, but the boiler was still heating the rads until 7.30pm when I eventually clicked the temperate down a degree on one on the thermostats - only then did the boiler shut-down.

Many thanks.

Didn't it occur to you to notice WHICH stat you turned down?

It seems to me it may be a problem on THAT channel.

Tony

 

[dk1uk]

Yesterday evening, I turned down the temp on the wired stat downstairs.

This morning the heating was programmed run from 6am-7am and it was still running at 8am. I turned down the temp on one of the upstairs wireless stats and the boiler shut-down so it doesn't seem to be an issue that's specific to a particular stat but later on I'll turn down the temp with the other wireless stat and report back.

In the meantime, any ideas? Razor900 asked about a bypass valve - how can I check if I have a bypass valve?

Thanks again.

 

[dk1uk]

Ended up living with this problem all Winter but hoping to deal with it this year before the weather kicks in.

Last year I could force the heating to shut off but clicking the temp down a degree on any of the stats.

How can the boiler remain on even when the programmer is telling it to switch off? It's as if the stats or wireless relay are able to bypass the programmer to keep the boiler running. As mentioned above, the boiler will eventually switch off but it can sometimes take an hour after the programmed time.

Does anyone have any ideas?

Many thanks.

 

[picasso]

Sticking microswitch or maybe the valve its self on one of your 2 port valves.

 

[dk1uk]

Thanks Picasso. I know what the 2 port valves are and how to check if they stick, but where would I find the microswitch and how can I tell if it's sticking? Thanks again.

 

[Steelmasons]

Possibly 24 volt room stat link hasn't been removed from PCB...

 

[dk1uk]

Hi - right the heating went on the first time this evening and the same thing happened...the boiler ignored the programmer and didn't shut the heating off. I left it for 15 minutes and then I turned down the wired thermostat to half a degrees below the currently displayed temp and boiler turned off.

Any ideas?