Zone Valve Problem?

[sloss]

Gentlemen,

I have a Multi Fuel boiler and an Oil Fired Boiler each able to run the CH and HW. (Free logs so the Multi makes sense)

When the Multi gets hot it inhibits the Oil Boiler and takes over the system via it's own Pump and 2 off Zone Valves.

It's worked fine for years but lately when the Multi needs to dump heat it's Pump starts up, the 2 off Zones are energised but the water fails to circulate properly. Temperature slowly rises downstream of the Pump and the Zone into the CH circuit but the return loop does not get hot.

The Pump sounds OK and I've manually opened the second Zone and indeed laterally taken the motor off it and it moves fine.

Question is, do Zone valves choke or is it more likely to be the Pump?

Pump is only 2/3 years old. I've tried it at all it's speeds - no difference.

 

[Softus]

Question is, do Zone valves choke or is it more likely to be the Pump?

It could be either of these, but my money is on the pump.

How are you preventing internal corrosion of your system?

 

[sloss]

Softus,

It's got Fernox in it and on bleeding rads etc it's clean and slightly soapy feel so seems OK.

I'll change out the pump and revert...

Thanks for your help.

 

[sloss]

I changed out the pump last night, tested it with the over ride switch and it all seemed OK as it got hot on return side of the return zone.

Lit the multifuel then sat back and waited until it needed to dump heat.

All worked fine and the multi kept the rads fine and warm.

Thanks for your help - back to lurking until the next problem crops up!

 

[Softus]

Good news indeed sloss!

If you had to drain down, I trust that you added a dose of Fernox when refilling.

 

[sloss]

Hi Softus,

I specified valves each side of my Pumps when the system was installed - nearly 20 years ago now!

They still operate/hold OK so it was just a quick change out.

The system was drained down 3/4 months ago to allow re-arrangement of the bathroom radiator and I added Fernox after that job. I watched the system draining then and was amazed how clean the water was - probably been in there for maybe 10 years since it's last draindown.

All I need is an occasional bleed of one radiator which goes cold at the top. Maybe 3 or 4 months between bleeds so it must be taking in makeup water to get the air but I can't find a leak anywhere.

How long does a good Copper Pipe system last?

Thanks again for your pointer,

 

[Softus]

I specified valves each side of my Pumps when the system was installed - nearly 20 years ago now!

They still operate/hold OK so it was just a quick change out.

Blimey - you're one of the few lucky ones!

I watched the system draining then and was amazed how clean the water was - probably been in there for maybe 10 years since it's last draindown.

Congratulations - you should pride yourself on engaging whoever installed it and on keeping it in good condition.

All I need is an occasional bleed of one radiator which goes cold at the top. Maybe 3 or 4 months between bleeds so it must be taking in makeup water to get the air but I can't find a leak anywhere.

It depends on how much 'air' you're getting out of that rad; it's possible that it's the result of the previous refill - I find that Fernox generates some 'suds' when it first goes in, and it seems impossible to get all the air out until after the system has settled for a few days.

How long does a good Copper Pipe system last?

Er, longer than a poor one and not as long as an excellent one.

 

[sloss]

The business I'm in requires that equipment that might need serviced/renewed should be removable without upset to the rest of the kit.

I've got full bore valves on both of my Boiler's feeds and returns.

It's changing out a rad valve or a Zone that's the Achilles heel.

I'd have thought it was 'normal' to use valves at these places I've mentioned to avoid disturbing the whole system and stirring up the crud unnecessarily.

 

[Softus]

I'd have thought it was 'normal' to use valves at these places I've mentioned

If you thought it was normal, then I wonder why you felt the need to "specify" them.

 

[sloss]

I'd have thought it was 'normal' to use valves at these places I've mentioned

If you thought it was normal, then I wonder why you felt the need to "specify" them.

If it's not on the 'Bill of Materials' then you don't get it is my experience....

The Oil Industry make me cynical.