Help - thermal store, mixer-valve replacement and cutting in isolation valves.

[Ben Ross]

Hi

My first post her but I was looking for some advice/to check that my thinking is correct about some work I want to do (I'm a willing novice). Ive got a wood pellet boiler and thermal store in the garage, feeding the central heating and hot water. Hot water storage and header tank in loft. A three way mixing valve needs to be replaced so I need to drain down the system and previous advice has suggested that I should also install some isolating valves to make it easier in the future. I think I'm fine with doing most of the work but have a couple of questionns/things to check. I've also mapped out the system in the garage in the hope that this helps (see below)



Flow - would I be right in thinking that A and B will both be expansion pipes, C as hot water out to house and D as cold in to system form header?

Location of isolating valves - any thoughts on locations?

Type of isolating valves to use - these are all 28mm pipes, copper in majority of system shown but plastic pipes to right hand side of pump on C and at D. I was looking at full-bore 28mm compression ball valves for the copper sections (is that correct and any ideas on where/what is best to get?), also can anyone recommend a product for the plastic sections if needed?

Drain down - there's a drain valve on the bottom of the thermal store. I'm fine with how to do this but wantedto check that all I need to do is to tie off the ballcock at the header tank?

Anyway, I hope this makes sense - any queries let me know. ANy help whatsoever would be very much appreciated.

Cheers

Ben

 

[jaydebruyne]

Hi

My first post her but I was looking for some advice/to check that my thinking is correct about some work I want to do (I'm a willing novice). Ive got a wood pellet boiler and thermal store in the garage, feeding the central heating and hot water. Hot water storage and header tank in loft. A three way mixing valve needs to be replaced so I need to drain down the system and previous advice has suggested that I should also install some isolating valves to make it easier in the future. I think I'm fine with doing most of the work but have a couple of questionns/things to check. I've also mapped out the system in the garage in the hope that this helps (see below)

View attachment 23250

Flow - would I be right in thinking that A and B will both be expansion pipes, C as hot water out to house and D as cold in to system form header?

Location of isolating valves - any thoughts on locations?

Type of isolating valves to use - these are all 28mm pipes, copper in majority of system shown but plastic pipes to right hand side of pump on C and at D. I was looking at full-bore 28mm compression ball valves for the copper sections (is that correct and any ideas on where/what is best to get?), also can anyone recommend a product for the plastic sections if needed?

Drain down - there's a drain valve on the bottom of the thermal store. I'm fine with how to do this but wantedto check that all I need to do is to tie off the ballcock at the header tank?

Anyway, I hope this makes sense - any queries let me know. ANy help whatsoever would be very much appreciated.

Cheers

Ben

If its a thermal store you shouldn't need to drain the system as the hot water should be on mains pressure and is heated from the standing water in the cylinder. You just need to isolate the mains cold and open up a low level tap to drain as much residual water from the pipework.

You can isolate the pipework to the right of the valve already with the pump valve but you shouldn't need to once you've isolated the mains.

 

[Worcester]

Typically we would install about a dozen full bore ball isolators on systems like that, think of the ability to isolate anything if it ever needs replacing, and drains at low points where you might to to drain down a small section, you don't want to be having to drain down the heating system or the store if you can avoid it.

Don't know who installed it, though from your description it looks more like a buffer tank than a thermal store. Also normally with a pellet boiler it's very unusual to have a three port blending valve on it (common on log boilers, not on pellet)

What make(s) of boiler, buffer tank, blending valve have you got?

How is the buffer tank charged? How is the blending valve controlled - looks like a Thermomatic K ?

I'm presuming it's also not RHI compliant as to be so it is definitely missing a bunch of isolators.

Plastic pipe not allowed on biomass installations.

Thermomatic K the head should be replaceable.