Boiler just always on....

[sxturbo]

fit a new motor, should fix your problem.

 

[Harry Bloomfield]

fit a new motor, should fix your problem.

I'm not yet convinced of that...

Ok thanks - progress. I took the actuator off and the valve moves easily with my fingers.

I re-fitted the actuator and then turned the heating on - no noise.
I turned the hot water on and the other valve/actuator makes a definite click/noise both turning on and turning off.

So do I conclude the actuator is dead? It definitely has power.

So, without turning the heating on and HW off - does the boiler come on and the radiators heat up?

If the answer to that is a definite NO, it seems your CH actuator was jammed in heating mode and the motor has also failed.

Switch the CH timer to on and stat to max, does the valve now move and the boiler run?
That suggests it is unjammed and working, but very likely to jam again. Worth fitting a new actuator.

Switch the CH timer to on and stat to max, (as above) if the valve doesn't move at all, then it is probably the motor in the actuator which has failed.
Actuator motors can be had for around half the cost of a new actuator, but as your actuator has jammed previously, it is worth fitting a complete new replacement actuator.

Get the details from the label stuck on the side and do a search for one on ebay/amazon. Carefully note the wire colours/connection before you start swapping them and make sure the power is off.

 

[solidpro]

So, without turning the heating on and HW off - does the boiler come on and the radiators heat up?

The way you've worded it is difficult to answer. If I switch on the boiler's isolator it will just central heat the house until we all cook.

Turning the hot water on after that does click the actuator going into the hot water cylinder.

Turning the boiler's isolator switch off and on or turning the hallway controller central heating controller off or on does nothing - that actuator never clicks or does anything. And it definitely has power.

A guy 3 miles from me is selling an exact brand new honeywell replacement for £60 (using the model/part number on the actuator's outer casing), so I'm going to go and get it now, fit it and see how I get on then...

Thank you for all your help so far, I'll report back in a few hours when it's fitted...

 

[Harry Bloomfield]

A guy 3 miles from me is selling an exact brand new honeywell replacement for £60 (using the model/part number on the actuator's outer casing), so I'm going to go and get it now, fit it and see how I get on then...

Almost certainly, a good move

 

[solidpro]

Ok so closer possibly to resolution. I didn't realise that both these actuators have a metal override lever on top which switches between automatic and manual open. That helps with the aligment as well as hearing what the noise should down like. The D shaped spigot took a few attempts to align seeing as I swapped over just the actuator, not the valve itself (would require a plumber who actually knows what they're doing).

Anyway, the new actuator is in place and it now clicks with the on or off of the house heating control unit and when it switches off I can actually hear the actuator turning. I don't understand why I don't hear it turning when switching on but maybe there is a simple explanation for that.

I'm waiting for a few hours for the house to cool down and then I'm going to do a full 'normal' test with switching the hot water on and checking no radiators get warm and then setting the central heating on and off to ensure the boiler follows these controls....

 

[stem]

when it switches off I can actually hear the actuator turning. I don't understand why I don't hear it turning when switching on but maybe there is a simple explanation for that.

There is. The motor is operated to open the valve. It works via geared connection so whilst the motor spins fairly quickly it's not unusual for the valve to take up to 8 to 10 seconds or so to open fully, so it's inaudible. The motor remains powered all of the time the valve is open in order to hold it open, and it 'stalls' when the valve mechanism reaches the limit of its travel. When the valve closes, power is removed from the motor and a spring pulls the valve closed in a couple of seconds. As a result of the gearing, and the forces generated by the spring, the motor is spinning approximately 5 times faster in reverse to close, than when it opens. Therefore you hear it.

 

[solidpro]

There is. The motor is operated to open the valve. It works via geared connection so whilst the motor spins fairly quickly it's not unusual for the valve to take up to 8 to 10 seconds or so to open fully, so it's inaudible. The motor remains powered all of the time the valve is open in order to hold it open, and it 'stalls' when the valve mechanism reaches the limit of its travel. When the valve closes, power is removed from the motor and a spring pulls the valve closed in a couple of seconds. As a result of the gearing, and the forces generated by the spring, the motor is spinning approximately 5 times faster in reverse to close, than when it opens. Therefore you hear it.

Thanks that does make sense. I've done several tests now and everything now seems to be behaving as normal. I now understand what those metal boxes are and vaguely what they do! I'm not quite 100% on how that failed actuator was keeping the heating on all the time though...

 

[Harry Bloomfield]

I'm not quite 100% on how that failed actuator was keeping the heating on all the time though...

Actuators operate in hot conditions which dries the lubricant out, then they jam. The thermostat signals the actuator to move. The clicks you hear are the micro-switches, operated by cams in the actuator, signalling the boiler. The micro-switches tell the boiler that the valves has opened fully and that the boiler should light up and run.

As it was jammed, your wall thermostat was having no effect and the actuator was just constantly calling for heat. It might be worth your while keeping the old removed actuator, opening it up, greasing the moving parts with high melting point grease, then reassembling and testing it to check if it works. If it does, you then have a ready to install spare actuator for next time one fails.

Actuators seem to be the most common failure on an heating system, so always worth having a spare to hand.

 

[solidpro]

As it was jammed, your wall thermostat was having no effect and the actuator was just constantly calling for heat. It might be worth your while keeping the old removed actuator, opening it up, greasing the moving parts with high melting point grease, then reassembling and testing it to check if it works. If it does, you then have a ready to install spare actuator for next time one fails.

I was thinking of doing that because I like to have a spare, but I'd made the guess that because it wasn't even clicking it was likely that the micro switch had actually failed outright and seeing as there were direct replacements available on ebay, new, for £35 it would be better to have a new replacement than spend any time at all trying to make this 20 year old one good again (perhaps only to fail in a different way later?)...

Thanks!