C type neutraliser

[Inverness]

Hi guys, went to look at a boiler replacement. Gravity cylinder with a fire that's connected to the neutraliser and a oil boiler that's connected too.all open vented system. The cylinder has not got a cylinder stat?! Either any zone valves?!
The hot water apparently boils as the fire is unregulated heat source and there's no boiler interlock.

I recommend to remove the neutraliser and keep the fire as a dry heat and pipe up the system to a s-plan and incorporate a room stat.

Any advise is appreciate.

 

[SimonG]

Look at heating innovations h2 panel. Lot of info on their web site.

 

[Best]

Sounds like neutraliser not properly controlled.
There should be a pipe stat to control the fire I would think.
What sort of neutraliser is it?
If the customers wish to use their fire a lot, then it might be still a very good system. I have some still working well after 30 years

 

[Inverness]

There's a pipe stat on the fire pipes to kick the pump in. Dundsley c type directly under the hot cylinder. no cylinder stat or zone valves. Weird set up.

 

[Best]

There's a pipe stat on the fire pipes to kick the pump in. Dundsley c type directly under the hot cylinder. no cylinder stat or zone valves. Weird set up.

That sounds like basically the way I did them. The stat was sometimes installed on the neutraliser to switch pump on well before cylinder or fire would boil. The controls could be upgraded if carefully thought was given to the functioning of system.

 

[Ric2013]

If you keep the fire as a dry heat source then you need to remove the boiler. I've seen an argument that you cannot really leave it in safely, and I think I agree.
Simple alternative solution would be to add a heat leak radiator that will run on gravity to reduce overheating of the system. If you can get it on the primaries then you could potentially use a normal radiator TBOE in 22 as far as possible and an Aladdin autovent. You could fit a normally open 2PV that closes under motor power when the pump is running (if the cylinder is cold) if you want to be energy efficient and prevent the radiator being hot needlessly. You could also have a pump that forces the heating on when the cylinder is hot, but really any unregulated solid-fuel heat source should have a heat-leak radiator.
I think the standard level 2 textbooks show this kind of thing in some reasonable diagrams.

I assume your real problem is that your proposed boiler will not run open-vented and conventional thinking has it that you can't safely run solid-fuel as a sealed system? I wonder whether a water/water heat exchanger might solve this?

 

[Inverness]

My plan, keep fire as a dry heat and cut pipes in loft area filled with sand. Replace cylinder for a unvented and upgrade oil boiler to a condensing and connected the flow and return to the exciting fitted with a s plan but keep it is open vented.

 

[Ric2013]

I think I see your theory about the sand. You've mostly blocked the waterways but any steam can escape so no explosion risk, and, should the backboiler burn out, then you'd hope that not much smoke can get into the loft. No fire risk and almost nil carbon monoxide risk.
If you were to do that in my house, I'd agree it is probably fine.
But I think if I were to suggest doing the same with a gas appliance people on this forum would be jumping off the walls in panic and quoting every law in the land at me. I have commented in the past about the possibility of double standards on this forum. It's probably going to be fine...

 

[ShaunCorbs]

baxi actually approve keeping the back boiler in place as you cant remove the back boiler and keep the fire in working condition due to the flue ways etc

 

[Ric2013]

I suppose in fairness, it depends how likely the fire is to burn through the backboiler and cause a (hypothetical) leak of smoke. I expect it depends on what the backboiler is made from and how it is made. I can imagine a copper one would probably melt quite easily if run dry.

HETAS, of course, likes to say that the only safe way is remove it, but I suspect this is a simplistic cop-out of taking any responsibility: Risks from redundant solid fuel back boilers

Worryingly, the solid-fuel association agrees with HETAS on this: Is it safe to use a fire with a back-boiler which is drained of water?

I was thinking about this while riding my bike the other day and it occurred to me that the ONLY difference between the fire burning through the backboiler and burning through the flue lining is that the flue lining is designed to be used as is whereas the backboiler is designed to be water-cooled. After all, the fire might just as easily burn a hole in the chimney which is only prevented from being a hazard by periodic inspections and by the fact that if you have a smoke (CO) leak from an open fire it's usually pretty obvious because you can smell smoke!

If, however, the manufacturer of the backboiler is happy for it to be run dry, then it is both realistically and officially safe. Do we know the manufacturer of the backboiler?

 

[Inverness]

It's a solid fuel back boiler not sure the brand.

 

[SimonG]

Speaking at cross purposes. The baxi one is gas, this one is solid fuel.
Regulations require it to be removed. Poc's can leak once boiler burns through.