Failing NRVs

[Will_D]

Long time no post! Happy new year to all!

About 2 years ago I had an inset backboiler stove (Ború Chieftain) fitted in with the existing OFCH.

Each heating loop was fitted with a non-return valve.

Within 1 week the first valve failed - as in stuck open. To date 2 more have also stuck open.

I was told by a builder that this is a problem with wood/coal fired back boilers and the secret may be to add a chemical (scale remover/disolver or the like). AFIK when the system was comissioned no additives were added.

Any suggestions?

I know there are several additives (Fernox make a lot) for the heating loop but which would be best.

Trouble is that plumbing supply shops that I visit aren't run by plumbers any more!

 

[Ermintrude]

U have solid fuel and gas ch on same system?

 

[Nostrum]

Trouble is probably the plastic inners of the non return valve have melted/failed from the wood burner. You'll need ones suitable for solar or similar.

More to the point, what are they fitted for? Sound like a bodge if you need them, especially as it was fitted by a builder . . .

 

[Will_D]

Trouble is probably the plastic inners of the non return valve have melted/failed from the wood burner. You'll need ones suitable for solar or similar.

More to the point, what are they fitted for? Sound like a bodge if you need them, especially as it was fitted by a builder . . .

The system is a wood burning back boiler and an oil burner. The never run together!

The NRVs are fitted so that when one system is running the other system doesn't act as a radiator!

As the oil boiler and its pump would force hot water down the flow side of the back boiler and vice versa.

How else would you arange this?

The max water temp from the back boiler is about then same as the oil 50 60 60C. The wood burner is thermostatically controlled.

I don't think the plastic innards would have melted. It was fiited by a qualified plumber recommended by the stove supllier so it was not a bodge. The builder I mentioned just mentioned that he has heard of these NRVs failing when used in a back boiler situation.

Any advice on Fernox?

 

[Chalked]

Non return on the flow or return of a wood burning stove!!

Surlely an absolute no no?
Chance of sticking shut, never mind open.
Plus the fact that the " plastic" has melted, rings alarm bells as these would then have to be spring return and are too strong for gravity.

 

[lame plumber]

just because you never run the wood burner and oil boiler together doesnt make it right or legal as a system!

 

[Robert Tyrrell]

just because you never run the wood burner and oil boiler together doesnt make it right or legal as a system!

I'd have to agree with you there, and state that the two can be combined with a system of motorised valves. IMHO - just for the obvious safety reasons, I would never fit a NRV on the flow or return from a solid fuel boiler.
I'd also question the relevance of the heating engineer's qualifications at this point. are they HETAS qualified? If not then I think that you're also on dodgy ground with regard to your home insurance.

 

[SimonG]

Its been bodged together. Needs doing properly. End of.

 

[Nostrum]

The system is a wood burning back boiler and an oil burner. The never run together!

The NRVs are fitted so that when one system is running the other system doesn't act as a radiator!

As the oil boiler and its pump would force hot water down the flow side of the back boiler and vice versa.

How else would you arange this?

The max water temp from the back boiler is about then same as the oil 50 60 60C. The wood burner is thermostatically controlled.

I don't think the plastic innards would have melted. It was fiited by a qualified plumber recommended by the stove supllier so it was not a bodge. The builder I mentioned just mentioned that he has heard of these NRVs failing when used in a back boiler situation.

Any advice on Fernox?

Why would the whereabouts of the boiler effect a non return valve, how does it even know where it is?

the system is wrong, and depending on the where about's of the non return valves, potentially dangerous.

But... Think what you want and make your own decisions, fernox is the least of your worries by the sounds of it ( p.s I don't think fernox make an additive for failing non return valves)

What's the make of stove?

 

[Will_D]

Why would the whereabouts of the boiler effect a non return valve, how does it even know where it is?

the system is wrong, and depending on the where about's of the non return valves, potentially dangerous.

But... Think what you want and make your own decisions, fernox is the least of your worries by the sounds of it ( p.s I don't think fernox make an additive for failing non return valves)

What's the make of stove?

OP States: Ború

So how do you have a dual fuel system (two separate boiler/pumps) and stop reverse flow?

 

[Killy Bing]

.......there should be absolutly no need for non return valves on a correctly designed and installed system..

you've had a bodge.
if the builder has done the work himself i would seriously consider getting a hetas engineer in to find out all the issues

 

[SimonG]

OP States: Ború

So how do you have a dual fuel system (two separate boiler/pumps) and stop reverse flow?

By having it installed correctly by an experienced engineer. Did you diy

 

[Chalked]

OP States: Ború

So how do you have a dual fuel system (two separate boiler/pumps) and stop reverse flow?

Lots of ways.
Neutraliser is the simple way to link the two.

 

[SimonG]

Lots of ways.
Neutraliser is the simple way to link the two.

Aye but to do it properly it costs money.

 

[Nostrum]

Are you in Ireland?