Hot Water and dch won't come on together

[Lambothenovice]

Help!! Just replaced the actuator on a Sunvic DM 5651 which appears to be working OK can here the micro switches clicking on and off Reason for replacing is that I can get DHW separately and can get CH separately BUT when set programmer for both only the water comes on no heat to radiators.

The boiler is a Potterton NETAHEAT 16-22 which has just had the gaskets replaced on the HE side plates and had a good clean out.

Any suggestions from the experts most appreciated.

Lambothenovice

 

[Slugbabydotcom]

Start with a cold system
Turn on with a call for heating and hot water.
Feel the pipes around the diverter valve
The 'Pipe on the tee' is the hot water going in from the boiler. The other two should both get hot as you have a mid position valve.
One feeds the CH and the other feeds the HW cylinder.

If one of the pipes gets hot then you have got a wiring fault.

If both of the pipes get hot then the hot water circuit is robbing the heating of hot water. This could be due to the heating side being sludged up and can be alleviated by fitting a balancing valve on the return where it comes from the cylinder and/or flushing and balancing your heating system.

Check the manual air vent on the flow to your cylinder. What comes out?
water ?
air [then water]?
Nothing?
If its air then water this may sort out the problem.
If its just water it eliminates some other possible causes
If its the much less likely 'nothing' then you could have a blocked feed pipe. Post back for further advice

 

[Lambothenovice]

Have just taken the valve apart ie removed the spindle with the carbon/ graphite paddle and discovered it was not seated on the spring loaded pin properly. How it never fell thro' one of the 28mms ports I'll never know.
Is there a suitable replacement valve body which takes a Sunvic dm 5651 Actuator with 2 ports bing 28mm and 1 port to the tank 22mms.
This valve is past its best.
For now tho' the problem appears to be solved.

 

[ChrisR]

No, they're all equal connections. I expect yours is too, before adaptor was fitted to the HW.

 

[Lambothenovice]

Is there a one which has 3 ports of 28mms with a D shaped spindle which would fit into the D shaped female end on the actuator.

Can I obtain a 28 to 22mms connector easily.

I am only a novice remember.

 

[Lambothenovice]

Thought I would share the final remedy with you regarding the initial problem of not being able to get DHW and CH on at the same time.

As a last resort I bought a Grundfos 15-60 Super Selectric off ebay at less than half the list price and decided to fit it last night. Much to my surprise the 2 ball valves which have never been turned in over 25 years with a bit of effort turned and I changed the old super 4 in less than half an hour without draining down.

The state of the old pump was unbelievable one, the ceramic shaft had sheared at the bearing position and the ports were just about wide enough to pass water!!

More importantly this morning VOILA!! heating and water together and the heating didn't wake us up when it came on soooo quiet.

Thanx for all suggestions.