Hot water not working!

[simlondon]

Hi, please help!

My hot water is NOT working from the boiler, although the immersion heater in the storage tank DOES work.

A plumber that visited for other reasons (successfully replace motherboard on the Baxi Potterton Suprima boiler) advised that it looks like the Actuator (Honeywell VC4613) is not working and needs replacement (which I am comfortable I could order and fit, having performed a small amount of domestic electrical DIY in the past).

However when I remove the head of the actuator from the base (2-port valve), the pump (Grundfos Selectic) AND boiler both start to operate (REGARDLESS of whether the thermostat is set to OFF or MAX).

This presumably means a) the head unit somehow or other sending "start" signals (to the boiler and pump) when disconnected from its base, but b) that the head unit isn't picking up the appropriate signal from the thermostat?

Can anyone advise what I should do next to determine whether it is my Thermostat or Actuator that's the problem?

Any advice much appreciated!

Thanks, Sim

 

[Bambergaspipe]

Probably a three port valve, removing the actuator head will allow your valve to move freely. The motor chooses between hot water & heating, removing the motor will leave your boiler set or stuck on hot water or heating only, depending on what it is set for now, in your case Heating only. You can move the valve manually with a set of pliers to the mid position, which will allow you both hot water/heating.
It will obviously need replacing at some point unless you choose to visit your cylinder cupboard every day with pliers.

 

[simlondon]

Thanks for taking the time to reply.

It's definitely a two-port valve (i.e. on a single pipe, no branching) rather than a 3-port valve (the central heating is controlled by a second, separate 2-port valve which is working fine).

Does this mean that the head unit on my 2-port hot water valve still needs replacing, or is there any possibility that it could be something else (e.g. could the thermostat on the tank could be broken, given that the immersion heater - with its separate bimetallic strip thermostat - is also working fine)?

Am I right in saying that the thermostat controls the head unit by sending voltage when water is cold, and then the head unit in turn a) uses its motor to open the valve and b) controls the pump and boiler via the electrical junction box? Understanding this would I'm sure help me work out what's going on.

Thanks again, Sim

 

[Agile]

You seem a little confused !

Perhaps this will help?

The valve is closed by a spring.

When it is powered to open the motor opens the valve and when fully open operates a microswitch which powers the boiler and pump.

Tony

 

[Bambergaspipe]

Fine, you have a 2 port valve. which does exactly what I have told you but does not give you the option of choosing hot water /heating individually unless you turn down your room thermostat to give you hot water only or you turn down your cylinder stat to give you heating only.
It sounds pretty old. You can test your 2 port valve by selecting heating/ hot water & have someone upstairs to check to see if the motor opens. Simple.
Ignore this., I have just re-read your post. You seem to have one motor for heating/one for hot water You have a faulty motor to your hot water flow.Replace it.

 

[simlondon]

Thanks, have just phoned my plumber and he's going to come and replace the motor in the next few days. He says £65 parts and labour, that's cheaper than if I was to buy a new Actuator (£115) and replace the head unit myself.

If this doesn't solve the problem I'll let you know, otherwise thanks a lot for both your assistance!

Sim

 

[gas4you]

Thanks, have just phoned my plumber and he's going to come and replace the motor in the next few days. He says £65 parts and labour, that's cheaper than if I was to buy a new Actuator (£115) and replace the head unit myself.

If this doesn't solve the problem I'll let you know, otherwise thanks a lot for both your assistance!

Sim

That sounds very cheap or reasonable to me

 

[Bambergaspipe]

Thanks, have just phoned my plumber and he's going to come and replace the motor in the next few days. He says £65 parts and labour, that's cheaper than if I was to buy a new Actuator (£115) and replace the head unit myself.

If this doesn't solve the problem I'll let you know, otherwise thanks a lot for both your assistance!

Sim

That sounds very cheap or reasonable to me

His system didn`t have actuators mate, not interchangeable ones anyway. The plot thickens.