Hot water staying on all night despite controller being off

[Peter Laing]

Good Morning All,
Further to my previous post about my pump running all night, I've now done some further investigation at 3am this morning and realised it's different than I originally thought.

We have a Glow-worm Ultracom 30hxi boiler that feeds our central heating and hot water. It’s controlled by a Drayton Lifestyle controller. The pump is a Grundfos Type UPS 15-60 130 Part number 5952660 and there are two motorised values sitting below the pump - one for the heating, one for the hot water.

At 3am this morning, the pump was running and by feeling the temperature of the pipes, I established the two valves were set such that the pump was feeding the hot water tank. Downstairs, I checked the boiler and it was running, though the timer/controller said it was all off, which it should have been at that time of the morning.

The other thing I noted is that the boiler temperature gauge was steady at around 70 degrees, then every minute or two the boiler would fire up and the temp would rise to around 90 degrees, the cut out, when the temp would slowly fall to 70 again. Whilst the heating/hot water is working during the day, the temperature display goes between 60 and 80.

I'd confirmed this previously by setting a temperature monitor on the pump for 48 hours and right enough, this showed that the pump temperature was about 45 degrees whilst the heating/hot water was on, but when the heating/hot water went off at night (according to the timer controller), the temperature of the pump slowly rose up to about 55 degrees, by which time the heating kicked in again, i.e. 5am in the morning, when the temp of the pump fell sharply down to 45 degrees again.

This is all piecing together with my other problem posted elsewhere on this forum about our two power showers being extremely hot. This problem started around the same time I noted the pump was running all night. It seems like the boiler is running hotter than normal at night and probably super-heating our water all night.

Please help me understand what's going on here!

 

[SimonG]

Issue with two port valve giving a permanent live to boiler and pump.

 

[Peter Laing]

Thanks Simon - where would I find this two port valve? Are they easy/expensive to replace?

 

[daWilko]

Hi - The timer should rule the roost, but the sticky valve explains this (edited my earlier post 🙄)

 

[Peter Laing]

Thanks daWilko - can you explain this to me in a little more detail please? Which valve is sticky and how would this make the system run all night despite the controller being off?

 

[Gasmk1]

because the 2 port valve although a switch the timer only open the valve there is a pemanent live to the micro switch so if the valve sticks open or the microswitch is faulty it will supply power to the boiler

 

[daWilko]

Thanks daWilko - can you explain this to me in a little more detail please? Which valve is sticky and how would this make the system run all night despite the controller being off?

The 2 port valve towards the hot water likely to be faulty.

 

[townfanjon]

The 2 port valve towards the hot water likely to be faulty.

Yep, what make are the valves ?

 

[Peter Laing]

Hi, I'm still a bit confused by what you mean by 2 port valves, but if you mean the two electric valves (one for heating, one for hot water), they're Drayton Zone Valve Actuator, Actuator Code ZA5

 

[Gasmk1]

2 port means one inlet and outlet 3 port means 1 inlet 2 outlets pretty simpole terminology really thats the way we refer to them iether a 2 port zone valve or a 3 port (diverter)

 

[Peter Laing]

Thanks Gasmk1 - makes sense now you've explained it!

 

[Murdoch]

If the programmer is off for both water and heating , said valve shouldn't have any power to it......

 

[Riley]

It can they will have a permanent live so if the micro switch is stuck it doesn’t matter if the controls are off. Heating systems are just a series of switches

 

[Murdoch]

It can they will have a permanent live so if the micro switch is stuck it doesn’t matter if the controls are off. Heating systems are just a series of switches

Rarely does the permanent live go to the valve ...... in my experience as a spark...

 

[Riley]

I am not doubting your expertise as I am a firm believer in why have a dog and bark yourself, I actually use very good electrician for a lot of System testing. However rightly or wrongly we have come across this exact issue three times in the past couple of months where the boiler is getting a constant switch live back from the valve.

 

[Murdoch]

Its an interesting thread this .......... I've seen more failed 2 and 3 port valve micro switches in the last year than I would say in the previous 5 years .............. my best guess is carp inports.

I've also seen this where the controller had failed ..... so the PL was on all the time, despite what the controller indicated.

These can be a right paid to fault find, unless all the contacts are readily accessible.🙂

 

[Gasmk1]

 

[Peter Laing]

Hello again and thanks for all your suggestions and advice. I think the problem is now cured. Basically, I took the "box" off the front of both two port valves and tried to move the spindles on the valve with pliers - the heating one moved very freely, but the hot water one was much harder to move. I exercised it back and forth a few times and it did free up, so I put the the box back on it and it appears to work now!

I've monitored it for a couple of days now and I've seen the black lever on both valves move from open to closed when they should do, i.e. when the controller says, or the thermostat kicks in/out.

Double bonus is that our showers are both now operating at normal temperature too! Happy bunny. I'm not counting too many chickens though as chances are, it'll stick again, in which case I'll get it replaced.

Thanks again for all your help!

 

[dan_the_plumber]

Turn power off. Test to make sure it’s off. Take cover of two port valve off. Spray cogs with wd40, move manual lever backwards and forwards a few times. Usually cures sticking valve. If problem persists, then new valve

 

[Best]

Just a tip for anyone for the future, -The Drayton 2 port valves have a couple of common reasons for failure that causes the power to stay on.
The less likely is the valve spindle sticking, but it does happen with Drayton. Probably best replace entire valve if this happens and keep the old actuator as a spare.
The most common problem is the works inside the Drayton actuator have a spring I think which is attached to a piece of plastic and this plastic eventually snaps off. To test if this is the issue, simply remove actuator and give it a shake. If it rattles, the plastic part has broke inside and new actuator or entire valve required.