Drain down system?

[blup]

Hi

Would I need to drain dowm the entire ch system when replacing a motorised valve (three port) if there are isolating valves above and below the motorised valve. Above is a 22mm pipe supplying the hot water feed from the boiler. Below is a 15mm pipe rising up from the main pipe that feeds from the bottom of the cylinder coil.

There are no isolation valves on the pipes from port a and b feeding the rads and the tank respectively. These run from either side of the mv horizontally

Any guidance/advice would be much appreciated.

blup

 

[75pete]

Some makes of 3way valves do not need to have the system drained.
what is the problem with yours?
have you checked it out on the web to see if its possable to replace the head without draining?

 

[blup]

Thanks for the prompt reply.

The valve clicks on the HW setting and heats up the rads. The lever moves in time with the clicking. Occasionally it works withoutout a problem. Having trawled through all the posts looks like a poor contact/microswitch problem.

It's a honeywell 3 port mid positioned valve about 18 years old (but equivalent in appearance to the current model).

I have bought the replacement from screwfix with a view to replacing the head but am thinking of just doing the whole thing to avoid **d's law applying.

Cheers

blup

 

[75pete]

Your new one, i think would have a "bump" on its top. Your old one if its 18yr old, unless its already been changed for a newer one , will not.
The "bump" means that the top part can be removed for replacement with out the need to drain the system.

 

[blup]

Thanks pete, have checked and there is a "bump" on head so guess it must have been replaced in the interim.