boilermate ov a class / glow worm hxi overheat
- Thread starter gray134
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I cannot see how a boiler manufacturer could allow their product to be endangered by having pump over run controlled by another device they dont make.
In any case the instructions for the store may be years out of date and based on an expectation of a cast iron boiler rather than a light weight modern unit.
In the absence of information from the manufacturer's we have to apply good engineering principles to ensure residual latent heat is safely removed from the boiler HW when firing ceases.
Tony
In any case the instructions for the store may be years out of date and based on an expectation of a cast iron boiler rather than a light weight modern unit.
In the absence of information from the manufacturer's we have to apply good engineering principles to ensure residual latent heat is safely removed from the boiler HW when firing ceases.
Tony
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Well I got to read it and it has confirmed my expectations!
This is from memory so the words may not be exact replicas!
Firstly it says the boiler MIs must over ride any for the store. I expect boiler says it must control the pump to provide over run.
Later it implies the boiler does not even need a permanent live unless ...
Later still it says " if the boiler has a froststat then it must supply the pump and a permanent live MUST be connected to the boiler !!!!
I am sure the GW will have a frost protection built in so its wrongly wired on that count alone!
Now down to the instructions being way out of date:-
It talks about a MINIMUM temp diff of just 8°C. Few current boilers would want that!
It says the boiler should be set to a flow of 82°C. Condensing boilers are now designed with a flow of 70°C in mind! Would not do much ( any )condensing with a return of 74°C either !!!
It shows the pump in the return! I cannot see anything wrong with that but for the last 20 years conventional systems have normally put the pump in the flow! ( Combis in the return though ).
So my conclusions are:-
The pump should be powered from the boiler!
The store instructions are not designed to fit well with the parameters of current boilers!
It would be irrelevant if it was properly connected but the store seems to be incorrectly timing the pump operation.
Connect the pump correctly to the boiler before you wreck it and find the damage is not covered by the guarantee !!!
Tony
This is from memory so the words may not be exact replicas!
Firstly it says the boiler MIs must over ride any for the store. I expect boiler says it must control the pump to provide over run.
Later it implies the boiler does not even need a permanent live unless ...
Later still it says " if the boiler has a froststat then it must supply the pump and a permanent live MUST be connected to the boiler !!!!
I am sure the GW will have a frost protection built in so its wrongly wired on that count alone!
Now down to the instructions being way out of date:-
It talks about a MINIMUM temp diff of just 8°C. Few current boilers would want that!
It says the boiler should be set to a flow of 82°C. Condensing boilers are now designed with a flow of 70°C in mind! Would not do much ( any )condensing with a return of 74°C either !!!
It shows the pump in the return! I cannot see anything wrong with that but for the last 20 years conventional systems have normally put the pump in the flow! ( Combis in the return though ).
So my conclusions are:-
The pump should be powered from the boiler!
The store instructions are not designed to fit well with the parameters of current boilers!
It would be irrelevant if it was properly connected but the store seems to be incorrectly timing the pump operation.
Connect the pump correctly to the boiler before you wreck it and find the damage is not covered by the guarantee !!!
Tony
good work Tony 
I agree with your findings. As I previously said in an earlier response I don't know how they are suitable for a condensing boiler because of flow temp
ps I always leave my boilers to run at 60C
I agree with your findings. As I previously said in an earlier response I don't know how they are suitable for a condensing boiler because of flow temp ps I always leave my boilers to run at 60C
I am comfortable with the concept of operating the store at up to 70°C from a condensing boiler. That will give a good balance between heat stored, CH output power and low risk of limescale.
Although my findings were very useful to me, as the store MI are clear and well written it did not take me very long to investigate.
Its a pity more people dont take the time to understand how these things work and how they are best set.
We have the arm chair experts like Water Systems on one side saying they are wonderful and the people who actually have to try to fix them saying they are a load of crap.
Properly inhibited and set up according to engineering principles ( Not their MI though ! ) I think they are capable of good performance.
Tony
Although my findings were very useful to me, as the store MI are clear and well written it did not take me very long to investigate.
Its a pity more people dont take the time to understand how these things work and how they are best set.
We have the arm chair experts like Water Systems on one side saying they are wonderful and the people who actually have to try to fix them saying they are a load of crap.
Properly inhibited and set up according to engineering principles ( Not their MI though ! ) I think they are capable of good performance.
Tony
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hmm interesting. the design does seem to be for older boilers......rather an oversight on gledhills part i think.
i know they are not the same model but ive worked on 4 boilermate systems this week....a BM2, 3 and 2000.
they all appeared to be controlling the pump....not the boiler even though the boilers had connections to do so.
i find it interesting that all three of us have now guessed the pump connections are at fault yet the gledhill engineer hasnt made this suggestion.....he has only stated the gloworm is "incompatible" in some unknown way. i had assume by the instructions that the pump could be controlled by directly running wiring directly from the boiler into the pump connections. why didnt he just do that then?
i know they are not the same model but ive worked on 4 boilermate systems this week....a BM2, 3 and 2000.
they all appeared to be controlling the pump....not the boiler even though the boilers had connections to do so.
i find it interesting that all three of us have now guessed the pump connections are at fault yet the gledhill engineer hasnt made this suggestion.....he has only stated the gloworm is "incompatible" in some unknown way. i had assume by the instructions that the pump could be controlled by directly running wiring directly from the boiler into the pump connections. why didnt he just do that then?
Just took the front off my boiler, suprima unfortunately, this always has the pump controlled by the boiler pcb to enable over run etc, but have noticed that pump isn't connected as usual. Only perm live, switched live, neutral, earth.
Boilermate must be controlling it and the over run!
Boilermate must be controlling it and the over run!
The Gledhill engineer may be a staff engineer who has worked with them for a long time and has a rather fixed mindset based on traditional non condensing boilers with a big cast iron HE.
Of course ignoring frost stats on the boiler, as long as the store does provide a pump over run then that would work fine. It will also give a pump over run to older boilers without over run. That might explain why he might have never considered the pump should be connected to the boiler.
To give them their due, the Gledhill instructions are quite clear that the boiler MI over ride theirs but then no one ever reads MI do they!
Tony
Of course ignoring frost stats on the boiler, as long as the store does provide a pump over run then that would work fine. It will also give a pump over run to older boilers without over run. That might explain why he might have never considered the pump should be connected to the boiler.
To give them their due, the Gledhill instructions are quite clear that the boiler MI over ride theirs but then no one ever reads MI do they!
Tony
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Agile said:
sorry but i still find that unlikely.
to be fair to him though we are assuming the fault lies with the overrun when in fact the OP's posts really point to the pump not coming on for demand. the overrun was first suggested by gas4you.
I only came into this towards the end and as you say the original description is that the store brings on the pump 15 secs late!
Even more reason why the boiler should control the pump itself as adequately allowed for in the Gledhill instructions.
As the store instructions seem to be written with a very old fashioned boiler in mind perhaps they thought it was better for an old c.i. floor mounted boiler to fire for a few seconds before turning on the pump?
I can see no incompatibility with G-W boilers as long as the pump is correctly wired to to the boiler.
Hopefully the OP will soon report back that it has been corrected and all is working fine?
Tony
Even more reason why the boiler should control the pump itself as adequately allowed for in the Gledhill instructions.
As the store instructions seem to be written with a very old fashioned boiler in mind perhaps they thought it was better for an old c.i. floor mounted boiler to fire for a few seconds before turning on the pump?
I can see no incompatibility with G-W boilers as long as the pump is correctly wired to to the boiler.
Hopefully the OP will soon report back that it has been corrected and all is working fine?
Tony
nickso said:
yes nickso, after my last post about my suprima I think you are correct to dismiss the over run and go back to the original post. I still can't see what would be different with the Glow Worm though
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