How There must be at least 1000mm between the flow and return, which must give you at least 10c differential in favour of the flow.
Maybe, but NOT when the store is hotter than the stove.
How There must be at least 1000mm between the flow and return, which must give you at least 10c differential in favour of the flow.
Pressure and temperature relief valve near base of heat store (90-95degC) opens natural circulation flow to heat dump radiator on 1st floor (power failure safety_)
You will never stop what is happening as long as you have a hole in your @ss.
You have made the whole system far too complicated for solid fuel with extra timers etc and it will never stop the store trying to heat the boiler if it is hotter.Hopefully you will realise that it should be pumped upto a neutral point in the system from either boiler and then to have the flow and return to the heating on tappings from that.
In effect the neutral point is doing what you want the alternatley switching motorised valves to do.Even if you pump the pipes from the solid fuel boiler you will still cool the heatstore as the temperature will even out regardless.Nice as your control system is admit that you have wasted time and money by expecting a solid fuel boiler to work like a gas or oil one,they take too long to warm up and the variable heat will always even out with being cooler at various times in the burning and heating cycle.
What you should have done is fit a dunsley nuetralizer as it works,and if your qualified installer had anything about him he should of suggested it to you.When the wood runs out the oil takes over,no timer is needed except on the oil boiler and the stats on the woodburner only need power.The woodburner should also of had at least somewhere for the excess heat to go i.e. heat leak circuit or a stat on the gravity return to dump heat into the radiators which should have been fed direct from the woodburner as an extra little cicuit.Nice as your control panel is it is unnessesary and will never work as you intend.
Please take a step back,cut your losses and fit a system that will work easily and will not leave your wife scratching her head and accept that solid fuel boilers are not supposed to work like regular boilers.
If you don't agree that's your perogative but I have seen all sorts of weird and wonderful systems over the last twenty years of working on solid fuel and people expect too much from them.
It's the main reson why I only fit dry systems now as manufacturers will tell you anything to get a sale but the reality doesn't live up to their claims,and you have to explain it to customers who don't believe you.
I have no arrogance in what I say but am just being an experienced realist .
Best regards
Parkymike...
I dont quite agree he should srap the lot because it isnt right. As for neutral zone to run everything from that doesnt have to be a Dunsley. The heatstore can become the neutral zone by quite simply running the flow and return from heating directly to it using flanges.
A dunsley neutraliser is nothing more than a small cylinder with multi tappings.
How There must be at least 1000mm between the flow and return, which must give you at least 10c differential in favour of the flow.
Maybe, but NOT when the store is hotter than the stove.
You will never stop what is happening as long as you have a hole in your @ss.
You have made the whole system far too complicated for solid fuel with extra timers etc and it will never stop the store trying to heat the boiler if it is hotter.Hopefully you will realise that it should be pumped upto a neutral point in the system from either boiler and then to have the flow and return to the heating on tappings from that.
In effect the neutral point is doing what you want the alternatley switching motorised valves to do.Even if you pump the pipes from the solid fuel boiler you will still cool the heatstore as the temperature will even out regardless.Nice as your control system is admit that you have wasted time and money by expecting a solid fuel boiler to work like a gas or oil one,they take too long to warm up and the variable heat will always even out with being cooler at various times in the burning and heating cycle.
What you should have done is fit a dunsley nuetralizer as it works,and if your qualified installer had anything about him he should of suggested it to you.When the wood runs out the oil takes over,no timer is needed except on the oil boiler and the stats on the woodburner only need power.The woodburner should also of had at least somewhere for the excess heat to go i.e. heat leak circuit or a stat on the gravity return to dump heat into the radiators which should have been fed direct from the woodburner as an extra little cicuit.
Nice as your control panel is it is unnessesary and will never work as you intend.
Please take a step back,cut your losses and fit a system that will work easily and will not leave your wife scratching her head and accept that solid fuel boilers are not supposed to work like regular boilers.[
cbell wrote
Pressure and temperature relief valve near base of heat store (90-95degC) opens natural circulation flow to heat dump radiator on 1st floor (power failure safety_)
Can I ask what type of valve you used here?
cbell wrote
Pressure and temperature relief valve near base of heat store (90-95degC) opens natural circulation flow to heat dump radiator on 1st floor (power failure safety_)
Can I ask what type of valve you used here?
In the end we didn't.
When designing the system I was worried that I didn't have a significant heat leak in the system, so I decided that I wanted a heat dump radiator on the 1st floor of the house working by gravity since the real danger condition is during a power cut when the (electrically pumped) overheat protection won't work.
I would (and do) still fit a safety valve to the store, it's the last stop before explosive burst mode and they're cheap. It is possible that the open vent pipe could freeze or the cold feed could block with limescale.
The T&P relief valves open full bore on temperature activation and are meant to allow cold water into the unvented cylinder to cool it rapidly.
How could a heat dump radiator on the first floor disspiate heat by gravity from a heat store on the second floor?
I appear to be shot down in flames for my post but I know that a dunsley sytem is designed that way for a reason and it works.
Your system works intermittently and I can see various things that should be done differently,If you persist which you will because pride won't let you fail(which is a good thing)I wish you the best of luck,but I have dealt with systems that have been added onto and altered to try and make them work and unfortunately they never give full satisfaction.I learned experience the hard way and the long way.
One other thing to consider is that now you have made your own control system box to work it all,Did you get it tested and approved to a suitable standard because if something ever goes wrong with the wiring like a fire your house insurance will walk away.Using parts already in the market your o.k.
Once again best regards
Parky
But if the feed/expansion tank is frozen (a near certainty in that scenario) where's that cold water going to come from??? (And the displaced hot go to?).
Actually, now I think about it, an ordinary oil or gas-fired CH system could just as easily explode in the "blocked vent and feed" situation, so I don't think we are in much more danger than before!?
There were no problems in the recent cold weather, which got down to -10 deg C overnight here. I can assure you that I was up there checking. Also with a fire every day, and a cut-off temp of 50 deg C at its top for heat extraction, the store only drops to 30 - 35 deg C, and this heat will be conducted up the vent pipe to keep it warm.
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