Replacing a 3-way valve

[OJ]

Hello everyone, from a complete newcomer to this Forum. This is my very first post, so I'd appreciate it if you could bear with me.

I need to replace the 3-way valve, positioned below my hot water cylinder, which switches the flow between central heating and hot water.

I have purchased a valve identical to the existing, and have a reasonable idea of the sequence of events which I need to carry out, but would feel reassured if someone with "the knowledge" would verify that I am on the right track...

1 - tie up the ballcock in the main tank (or the f&e tank) in the loft

2 - connect a length of hosepipe to the drain valve on the lowest positioned rad, and open the drain valve.

3 - open 2 or 3 bleed valves on the upstairs rads, to allow the system to drain. Is there a valve on the hot water cylinder?

4 - how do I kow when the system is sufficiently drained, other than by starting to undo the connection on the old 3 way valve?

5 - remove the old 3 way valve, and fit the new one (do I use boss white, ptfe, or?), together with the controller unit on top of it.

6 - shut off the drain valve, and any open bleed valves.

7 - add some (how much?) inhibitor (fernox?) to the tank in the attic, and untie the ballcock, to allow the system to re-fill.

8 - bleed all rads (start downstairs, or doesn't it matter?)

9 - fire up the boiler, and check that the switching works correctly.

10 - job done?

Any advice would be greatly appreciated.

Thanks, in advance.

OJ.

 

[Agile]

You dont have to drain any of the rads!

Close just one valve on each rad ! However leave the one rad valves open next to the drain point.

Tie up ball valve and drain from drain point anywhere below the valve.

Then slowly open connections to the valve and put something under neath to catch small amounts of water remaining in the pipes.

Tony

 

[leakydave]

I would fill system, check for leaks and have a cuppa before adding any inhibitor to the system... you don't want to lose it cos you've a leak now do you. You could always drain a bit from the system, litre or so, before adding to header tank.

Take a photo (mobile phone?) of the wiring centre cos it is easy to think you'll remember where it all goes, answer the phone and then forget what went where.

What were the symptoms of you thinking the 3 port valve needed changing by the way? Sure a new motor wont do what you want without draining anything??

 

[gas4you]

Bung open vent and cold feed (or turn off with cld fill gate valve if you have one.

A little water will be released but otherwise simple job, no need to drain down.

 

[Gas2Air]

You dont have to drain any of the rads!

Close just one valve on each rad ! However leave the one rad valves open next to the drain point.

Tie up ball valve and drain from drain point anywhere below the valve.

Then slowly open connections to the valve and put something under neath to catch small amounts of water remaining in the pipes.

Tony

Then replace 25 year old leaking rad valves

 

[ChrisR]

Noe noe noe you didn't wanna doooo that!
Is it a Honeywell vave, or a Danfoss...?

 

[OJ]

I would fill system, check for leaks and have a cuppa before adding any inhibitor to the system... you don't want to lose it cos you've a leak now do you. You could always drain a bit from the system, litre or so, before adding to header tank.

Take a photo (mobile phone?) of the wiring centre cos it is easy to think you'll remember where it all goes, answer the phone and then forget what went where.

What were the symptoms of you thinking the 3 port valve needed changing by the way? Sure a new motor wont do what you want without draining anything??

Thanks for that, leakydave. Why do I need to concern myself with any wiring? The Valve was all seized up - impossible to turn, without a spanner.

 

[OJ]

Bung open vent and cold feed (or turn off with cld fill gate valve if you have one.

A little water will be released but otherwise simple job, no need to drain down.

Thanks, but I'm afriad I don't know how to do that - can you tell me more, please?

 

[OJ]

Noe noe noe you didn't wanna doooo that!
Is it a Honeywell vave, or a Danfoss...?

Ummmmm, the valve is a TYPE MK, use with ACTUATOR TYPE DM, if that tells you anything...

 

[OJ]

I was hoping that someone could give me a complete overview of the whole job, rather than throwing in the odd one-liner - sorry, but if I knew how to do this job, I wouldn't need to ask for help - my 10 steps have lots of uncertainties contained within them......

OJ.

 

[gas_man_gaz]

i never go into the wiring centre i just snip the wire and put a junction box in, alot easier!
i wouldn't drain the system either id bung the cold feed and open vent and shut one of the pump valves, jus have a old towel under the valve and use a rubble bag to catch the bit of water what will come out..

why does the valve need replacing anyway?

 

[OJ]

i never go into the wiring centre i just snip the wire and put a junction box in, alot easier!

Why am I interested in any wiring?

i wouldn't drain the system either id bung the cold feed and open vent and shut one of the pump valves, jus have a old towel under the valve and use a rubble bag to catch the bit of water what will come out..

I don't have sufficient knowledge to understand any of that.

why does the valve need replacing anyway?

The Valve was all seized up - impossible to turn, without a spanner.

 

[gas_man_gaz]

iam guessing ya got a manual 3port valve then? (ya use a lever on the valve to direct the flow of the water to ch or hw) i thought ya had a motorised valve - dnt worry about the wiring bit

if ya go into the loft ya should hav a small tank with a vent pipe in the top and a feed from the tank to ya system. if ya can plug both these it will create a vacuum in the system so wen ya take the valve out only a bit of water should come out.. like the pint of beer and coster trick

 

[gas_man_gaz]

but ya need to close 1 of the pump valves as well!

 

[OJ]

iam guessing ya got a manual 3port valve then? (ya use a lever on the valve to direct the flow of the water to ch or hw) i thought ya had a motorised valve - dnt worry about the wiring bit

No, it's motorised, but it's the valve I need to replace, not the motorised actuator....

if ya go into the loft ya should hav a small tank with a vent pipe in the top and a feed from the tank to ya system. if ya can plug both these it will create a vacuum in the system so wen ya take the valve out only a bit of water should come out.. like the pint of beer and coster trick

Sounds too simple to be true? lol