Hot Water Timers

[Mr. Dazzle]

Well....I changed the controller today and replaced it with the same type again (almost...went for the 7 day timer instead) to no avail.

Looks like I'm getting a man in!

[Doc]

On a setup like yours, the thermostat on the side of your HW cylinder is what 'calls' for heat. It energises the HW zone valve, which in turn operates a microswitch as it opens. This microswitch calls for heat from the boiler.
The controller only determines when the circuit is live and thus able to call for heat.
Start with the cylinder stat. When the boiler is running, turn the stat down until it clicks. This should close the zone valve and turn off the boiler (the pump will probably run on for a minute or so). If this happens then it shows that the rest of the system is working.

[Mr. Dazzle]

I just tried to do that and the knob broke inside the stat.
The knob just spins freely

I think you may be on to something.

Hmmm....well that definitely broken one way or another.

[Mr. Dazzle]

The thermostat is probably a bimetal strip btw.

Ha....turns out you're right!

So I think i get how it works now, thanks to Doc's insight.

The thermostat has little microswitch in it (the little black box). That switch is actuated by a bimetallic strip which sits against the tank. By manually actuating that switch i can make the system open/shut the circuit valve (the grey box sat on my knee) and turn the main pump/on off.

I have a double problem in that the mechanical aspect of the valve is stiff so the actuator struggles to move it.

The adjuster in the stat is broken inside, so the bimetallic strip never turns the microswitch off and the tank just calls for hot water all the time. I have never touched this stat before in my life so fuck knows how it broke.

So yeah...broken stat! Every day is a school day.

The bit I don't quite get is why it would never turn off before even when the timer said it should be off. Did it just get stuck on waiting for a switch off signal that would never come?

[Doc]

If the mechanical part of the zone valve is stiff, waggling it open and closed with a pair of pliers might help to free it off. If the servo motor can't physically close the valve, the circuit will continue to call for heat from the boiler. It can also burn out the servo motor!

[Mr. Dazzle]

Servo motor is brand new. I was wrong about the valves BTW, its the other two circuits which have brand new valves. This is the only original one left in the system.

At the moment I've got the valve fully open and the servo on the floor next to it. I have just turned the stat over and the boiler comes on, turning it the other way up turns everything off again (literally gravity moving the switch) The man is coming on Weds...It's not gonna die like that is it?

[Doc]

I'd try and free the valve off and refit the actuator.
Manually switching it on and off by flipping it over shoukd be fine. Juat be aware that it's 240v across the contacts.

[Mussels]

I thought valves were meant to be slightly stiff so the motors move them gently.

[KungFooBob]

The Honeywell three way on my system is only powered one way, to return it uses a spring, if it's too stiff the spring can't turn it back to hot water

[Silly Car]

Fancy it being the thermostat, I’m surprised nobody mentioned it sooner…

[Mussels]

Fancy it being the thermostat, I’m surprised nobody mentioned it sooner…

He's an engineer, he needs a complicated answer.

[Mr. Dazzle]

I wanted a new 7 day programmer anyway, so no money wasted.

[KungFooBob]

But is it 7 day or 52?

[Mr. Dazzle]

52 days? What happens on the other 313?

[Mr. Dazzle]

Fancy it being the thermostat, I’m surprised nobody mentioned it sooner…

He's an engineer, he needs a complicated answer.

None of you lot explained what actually happens....what I'm supposed to just take your word for it?

Doc showed his working out.

[KungFooBob]

It's 5+2.

The five week days the same and two weekend days

Also, modern timers are not on/off, they use setpoints. So you have to set a set point to below ambient temp to turn off the heating.

Can you tell I've been making youtube videos on how to program thermostats this week

[Mr. Dazzle]

How does ambient room temperature effect my hot water? Or have you not got to that vid yet?

[KungFooBob]

You need a two zone programmer for that.

I've not got to our range of programmers yet.

[Mussels]

It's 5+2.

The five week days the same and two weekend days

Also, modern timers are not on/off, they use setpoints. So you have to set a set point to below ambient temp to turn off the heating.

Can you tell I've been making youtube videos on how to program thermostats this week

My old school room stat uses a capacitor to achieve the same result.

[KungFooBob]

I'm IT, I have half an idea on how to use Adobe Premier Pro so I've been roped into editing videos. I know next to fuck all about the products.