Heating problem

[marksh]

Hi Guys,

I have a Potterton heating system in my house with 9 radiators (without TRV’s) scattered around the house.

All of a sudden last week the CH completely stopped working and the HW was scalding hot. The CH pump was working ok and I could feel the hot water circulating through it but I just could not work out why the radiators were not getting hot. I then suspected an airlock I the system. So over the weekend I turned off the heating system, and the water feed to the F&E tank in the loft. I then turned on the valves on the radiators fully open. I then connected a pipe from the outside tap to the bottom of the lowest radiator in the house and got the missus to turn the water tap on and off while I watched the F&E tank in the loft. I did not notice any air bubbles appearing in the F&E tank…strange I thought.

Anyway, I then turned the system back on thinking that was the end of the problem. I made sure the pump was running and hot water was circulating through it as before, everything seemed fine except….the radiators were not getting hot!! Anyway, after kicking the cat, I sat and thought and at the time did not think to check the motorised valve. It is a MSV322 (ACT322 actuator) 3 port valve and the neon lamps were on as normal. I then took the ACT322 actuator off the valve unit and turned the valve with a pair of pliers and…..the radiators started warming up!!! I have discovered that the ACT322 actuator has finally seen better days. I have left the actuator hanging off with the valve in the mid position until I get the actuator sorted.

My question is to the more expert of you all…

Is it possible to fix this actuator? If it’s the motor inside the actuator, where can I get a new motor? If it’s the components, are they easy to get and replace?

Cheers all.

 

[gremlin16]

Actuator heads are available. Not sure if motors are replacable.
Type Potterton Myson ACT322 Actuator in search engine then find cheapest supplier.
Easy to change as long as you dont mix the wiring up!





Potterton Myson ACT322 Actuator

Part No. 421001

 

[MANDATE]

The valve spindle should turn quite easily with finger and thumb. If its stiff it makes it hard work for the motor. have found using plastic tube and hand drill makes it easy to revolve while applying WD 40.
If the motor is the fault, it will never reach the CH only position.

On the other hand if it does reach the CH only position and boiler does not light then the cause will be one of the micro switches.
New actuator will resolve your problem (if spindle is free)
Got one about a month back. Best deal was 'heatingonline'.
Two more tips when wiring in.
(a) make sure the system is without power and fuse removed. Just turning the HW and CH off at the programmer is not good enough! there is still a 'live' grey from the HW OFF terminal.
(b) You may like copy what I did( well I didn't actually do it but arranged it)
Mounted a ordinary 25mm deep switch patress close by. Instead of fiddling with the 10 terminal box to search for the wires the existing cable was cut and the wires put into choc block terminals and the new cable was connected accordingly. Switch patress covered with blanking plate.
Any future changes will be simple. Also easy access for testing and by-passing if micro switch fails.

 

[marksh]

Hi Guys,

Many thanks for all your help. I decided it was too much trouble to try to repair the old actuator (ACT322) and to just to buy a new one.
I got the new actuator from Heating Controls Online (http://www.heatingcontrolsonline.co.uk) for a total of £41.60 (inc. Postage & VAT). I know that maybe slightly more expensive than another supplier but only a matter of a few quid.

I wired in the new actuator and now the system is working perfectly – Phew!