Primary Circuit Backflow in Solid Fuel / Oil Fired system

[Solid Fuel]

---

Hi
Question on how best to design/solve back flow in a Solid Fuel Primary circuit. This is happening when the fire is not lighting and the oil fired boiler is operating into the common dual coil copper cylinder causing the idle stove coil to heat and thus starting back-flow in its circuit drawing out the heat generated eventually cooling down the cylinders hot water.
Pls see attached for basic current layout.

System is operating in bungalow house.

Thanks for any feedback
View attachment Primary Circuit.zip

 

[rjscan]

Invest in System link box look it up on the net

 

[Solid Fuel]

Tks
Aware of the systems but still wondering what is the other methods available !!

 

[SimonG]

It's piped incorrectly and you show no heat leak. It's not the way to do it.

 

[Solid Fuel]

I negated the heat leak from drawing (fair point tks), have heat leak rad on wall higher than stove in hall other than that system is working fine i.e only issue is backflow when idle which I am looking for historical method if you like of the fix.

 

[SimonG]

Pipe it correctly, problem solved.

 

[Solid Fuel]

Hi
That is the advice I am looking for on what is the correct piping !!

 

[Solid Fuel]

Primary Circuit Backflow in Solid Fuel / Oil Fired system

---

Hi
Question on how best to design/solve back flow in a Solid Fuel Primary circuit. This is happening when the fire is not lighting and the oil fired boiler is operating into the common dual coil copper cylinder causing the idle stove coil to heat and thus starting back-flow in its circuit drawing out the heat generated eventually cooling down the cylinders hot water.
Pls see attached for basic current layout.

System is operating in bungalow house.

Thanks for any feedback​

 

[Gray0689]

Your flow from stove is gravitating back from cylinder
You need to put on a flap non return ( not a spring valve) on flow from stove
Where is the pipe stat and I'm presuming you got non return valves after pumps

 

[Best]

As far as I know, you are not supposed to fit a valve on the primary circuit of solid fuel. Bungalows all have this problem with direct linked back boilers & indirect heating boilers.

 

[Solid Fuel]

Stat on pipe just before hot water tank, got non return after both pumps.
Circuit is working perfect other then this glitch which I would like to sort.
Tks for reply's

 

[Best]

There is nothing you can do with this, as far as I know, as the primary flow in a bungalow, rises above the cylinder. This will always allow the heat to travel back to fire overhead. A flap door type check valve fitted on the primary return between cylinder & fire feed pipe will stop this & still leave open vent & feed if something happened valve. But I repeat, I think this is not allowed.

 

[Solid Fuel]

Hi
Yes the principle is not to have any mechanical restriction in the primary circuit for obvious reason but I was wondering has or is there any other method i.e. construction of pipe bends to create air break or dead leg but still not interfering with the natural flow when required. Basically any tricks !!

 

[Best]

Bar, putting the cylinder in the roofspace, in a bungalow, which would mean the hot water wouldn't go downwards, then I see no way of stopping it. It is the flow that is the problem & this can't be fitted any other way than it should. Once the heat starts to rise up the pipe in hot press, the return replaces it, thus starting a circulation. So nothing you can do with bending pipes different ways.

 

[ecowarm]

It would be better if it had a neutral point i.e neutralizer or link up system. But as it is now flow and return should rise to cylinder not drop down like the return and also I would also have the flow rising all the way to cylinder connection. But as said it would be better with a neutral point or have a look at the H2 Panel.

 

[Solid Fuel]

Hi
I have seen products like this and went for the basic set-up at present (cost been a factor) and opted to, if you like to suck it and see in relation to dropping back down from the roof space to my hot tank, flying in the face of the constant rise to the cylinder given the current house configuration. That said the flow and return path I am very happy with, as tested with full fire from cold on windy day it heats and moves water fine around the circuit.
I think for present so far it looks like I will have to conceded to the backflow unless another simple option appears on the horizon.
Tks for reply.

 

[Gray0689]

You really only have one option that's a flap non return valve if you don't put it on your hot water will not last long at all

 

[ecowarm]

I suppose you could put a normally open 2 port valve on the return operated by a stat on the flow so if no heat in solid fuel boiler valve shut and in a power cut valve returns to open. Please check regulations as to wether this is allowed

 

[Solid Fuel]

Thinking that but will this affect my flow much. Have you fitted these with good affect.

P

 

[ecowarm]

Fairly full bore, slight restriction, not much though

 

[dontknowitall]

I suppose you could put a normally open 2 port valve on the return operated by a stat on the flow so if no heat in solid fuel boiler valve shut and in a power cut valve returns to open. Please check regulations as to wether this is allowed

I don't know much about solid fuel (learning) but I think this one is allowed. I was scratching my head earlier as I have been shown how this was done to keep within regulations, safety, etc. The trick is the "normally open" 2 port valve - I think!

 

[Solid Fuel]

Ever fitted a flap non return valve in circuit and no adverse affect to flow.

 

[SimonG]

Should have 2, one to heat leak that fails open and one to cylinder that fails closed to protect cylinder in case of power failure.

 

[ecowarm]

I don't know much about solid fuel (learning) but I think this one is allowed. I was scratching my head earlier as I have been shown how this was done to keep within regulations, safety, etc. The trick is the "normally open" 2 port valve - I think!

Thats correct DKIA in green

 

[Solid Fuel]

Ever fitted a flap non return valve as suggested in primary circuit.

 

[Best]

Seen it done, & it works, providing it's fitted right, but can't see it being allowed.

 

[Gray0689]

Works perfectly and it is allowed

 

[Best]

Works perfectly and it is allowed

I wasn't sure if it was allowed or not, as some info says no valves on primaries, but I suppose this is to stop gate valves etc being fitted by idiots. I just don't like to tell anyone to mess about with the primary circuit if they are not experienced. I have no problem with a flap valve fitted on return, between cylinder, personally, & to be honest, have fitted them.

 

[Gray0689]

No valves allowed that can be shut off like you said gate valves ect

 

[Best]

Thanks Gray, I will feel happier fitting them in future, - if I can buy flap valves easily anymore, as merchants seem not to have them!