2 gloworm boilers in parallel both producing fault codes f25
- Thread starter Anwah
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HI Agile i have updated the thread to try and give more accurate info
i dont know about the megaflow / 60kw equation im just writing down
what the parts in the system are. I couldnt isolate boiler as you sujested
because their are no isolating valves above the boilers. I spoke to the plumber about this and the LLH that had brrn sugested he said he will do anything that will give a solution to the problem.
I have 5 good pictures of the system but i cant attatch them to the post
because i dont know how, i have asked for help in a couple of posts
above but it was late last night.
i dont know about the megaflow / 60kw equation im just writing down
what the parts in the system are. I couldnt isolate boiler as you sujested
because their are no isolating valves above the boilers. I spoke to the plumber about this and the LLH that had brrn sugested he said he will do anything that will give a solution to the problem.
I have 5 good pictures of the system but i cant attatch them to the post
because i dont know how, i have asked for help in a couple of posts
above but it was late last night.
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Could I then recommend you consider installing it similar to this on the boiler side but your boiler won't have the built in pumps
View media item 18024
View media item 18024
Hi lcgs have you got a better copy of the diagram because it is very faint
and when i zoom in it goes blury. Can you tell me how to post pics from the album in my profile because i have 5 pictures of the system.
and when i zoom in it goes blury. Can you tell me how to post pics from the album in my profile because i have 5 pictures of the system.
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www.vaillant.co.uk/stepone2/data/downloads/3c/43/00/commercial-heating-brochure.pdf
page 6/7
id be looking to fit a pump on each boiler return,as the drawing is based on a system boiler with internal pump,or 1 large shunt pump serving both boilers.
as for photos,if youve uploaded them into your album,then use the show my images option to insert them.
if your struggling email them to me and i'll pop them up for you(emails in my profile)
page 6/7
id be looking to fit a pump on each boiler return,as the drawing is based on a system boiler with internal pump,or 1 large shunt pump serving both boilers.
as for photos,if youve uploaded them into your album,then use the show my images option to insert them.
if your struggling email them to me and i'll pop them up for you(emails in my profile)
Hi Lcgs thanks for your help, i have now loaded the pictures that people have been asking for , what are your thoughts on the low loss header. If we fit 1 we may make it ourselves but we would need to know the dimensions i have downloaded the diagram off the Kelston site but i dont know if this is ok for our system we have also got to fit check valves that Argile sugested we do.
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Personally I'd always fit a llh to multiple vaillants,you might as well buy vaillants own header it's about £140 and saves the messing of having to make one.
Trouble is to get it in you'll be repiping a lot of what you've done.the 4zones you have if your fitting a header,you can wither install one system pump to do them all and leave the 2ports in plus bypass or replace the two ports with individual circuit pumps.
What ever you do it's now hard work.
Simplest solution could be to fit bigger pump allowing for the high kpa of the boilers and the system.
Its a personal thing but I don't like to see 35mm pipe feeding a 15mm ported pump(your alpha),oh and just as a by note those boilers don't like modulating pumps.
P
Trouble is to get it in you'll be repiping a lot of what you've done.the 4zones you have if your fitting a header,you can wither install one system pump to do them all and leave the 2ports in plus bypass or replace the two ports with individual circuit pumps.
What ever you do it's now hard work.
Simplest solution could be to fit bigger pump allowing for the high kpa of the boilers and the system.
Its a personal thing but I don't like to see 35mm pipe feeding a 15mm ported pump(your alpha),oh and just as a by note those boilers don't like modulating pumps.
P
Thanks we were intending replacing the alpha with a light comercial that we have allready. and we were thinking of using the alpha as a shunt pump.
The quality of the installation is generally not bad which surprised me because of the three main so basic problems which I see with its operation.
They are:-
1. Pump grossly undersized for boiler power.
2. A boiler sequencer fitted with no provision to stop back flow through non-op boiler.
3. No way to isolate either boiler for maintenance or testing.
Does the property really need 60kW of boiler power? Use whole house calculation to see whats really needed.
Tony
They are:-
1. Pump grossly undersized for boiler power.
2. A boiler sequencer fitted with no provision to stop back flow through non-op boiler.
3. No way to isolate either boiler for maintenance or testing.
Does the property really need 60kW of boiler power? Use whole house calculation to see whats really needed.
Tony
Hi Agile- I asked the owner of the house which is at the moment a 5 bed detached property what he had planning permision for and he said it would it would end up being 9 bedrooms . I will ask the plumber to check calcs like you suggested. Who do you use for reasonable priced check valves ?
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Don't get too concerned over agile banging on about you having 60kw,what he forgets is most cascades are sized so each boiler on it's own could run 2/3rds of the load,this give good redundency and also if you read vaillants literature gives you increased efficiency.
The reality is you need to size it to work at it's full 60kw,then you can down rate the boilers to match the load,no point downrating first then sizing to suit 40kw per say as any further extension won't be catered for.
PartL also advises you allow for future extensions by overdosing by a certain percentage.
In fairness to the installer it looks ok,the lack of isolation isn't ideal but the instructions don't say you must but it's good practice.
Can I ask why to heat only and the robo kit when 2system boilers would have given you less hastle
The reality is you need to size it to work at it's full 60kw,then you can down rate the boilers to match the load,no point downrating first then sizing to suit 40kw per say as any further extension won't be catered for.
PartL also advises you allow for future extensions by overdosing by a certain percentage.
In fairness to the installer it looks ok,the lack of isolation isn't ideal but the instructions don't say you must but it's good practice.
Can I ask why to heat only and the robo kit when 2system boilers would have given you less hastle
HI Lcgs- The plumber said when he did the calcs it came out at 50 kw.
Can you enlighten me to what a robo kit is. We have got at least 6 sytems
we have installed exactly the same and never had problems with also running
with 15/60 pump.
Just like to add the plumber chooses the boilers and requested me to fit a sequencer for equal wear on the boilers. Im not sure why he doesnt fit boiler isolators as standard but it may be to reduce the overall cost of the system
after the advice we have had from you guys , we will be using them in future.
Can you enlighten me to what a robo kit is. We have got at least 6 sytems
we have installed exactly the same and never had problems with also running
with 15/60 pump.
Just like to add the plumber chooses the boilers and requested me to fit a sequencer for equal wear on the boilers. Im not sure why he doesnt fit boiler isolators as standard but it may be to reduce the overall cost of the system
after the advice we have had from you guys , we will be using them in future.
Lee seems to be considering this a a new requirement which you are now going to install to meet the requirements.
The reality is that you have an existing installation which you will want to get working with the minimum to be done.
Check valves are only required when you have one pump per boiler. You dont have that!
To enable the sequencer to work properly, you need to add some way to stop any flow through the "off" boiler. While that would usually be achieved by one pump per boiler with check valves, in your case it would have to be with a motorised valve. That will have to be installed so that an over run delay can be provided to enable the boiler to cool down.
The better solution will probably be to add a pump so that each boiler has its own pump. That will also enable the flow/return differential to be more accurately retained when only one boiler is in use.
Isolation valves enable maintenance/replacement to be done while the second boiler continues the service. It seems very odd to fit a boiler without them.
If the heat needed is really 50kW then 60kW of boilers is reasonable. But I am surprised if the heat requirement really is that high. I fitted a 24 kW boiler to a large 5-6 bed detached house and that still cycled off when its was below zero outside.
Tony
The reality is that you have an existing installation which you will want to get working with the minimum to be done.
Check valves are only required when you have one pump per boiler. You dont have that!
To enable the sequencer to work properly, you need to add some way to stop any flow through the "off" boiler. While that would usually be achieved by one pump per boiler with check valves, in your case it would have to be with a motorised valve. That will have to be installed so that an over run delay can be provided to enable the boiler to cool down.
The better solution will probably be to add a pump so that each boiler has its own pump. That will also enable the flow/return differential to be more accurately retained when only one boiler is in use.
Isolation valves enable maintenance/replacement to be done while the second boiler continues the service. It seems very odd to fit a boiler without them.
If the heat needed is really 50kW then 60kW of boilers is reasonable. But I am surprised if the heat requirement really is that high. I fitted a 24 kW boiler to a large 5-6 bed detached house and that still cycled off when its was below zero outside.
Tony
Hi Agile- Would i need 1 or 2 motorised valves and where would you advise i put them ?
Im assuming i couldn't mount them in the 35mm pipework could i ?
The pump that is their at the moment is controlled by both boilers and has an overrun of 5 minutes could i link the valves with the pump wiring so they close
when the pump stops ?
Or i put the check valves inbetween the boilers on the flow and return and put a bigger pump where the alpha is at the moment and we could possibly use the alpha as a shunt.
Im assuming i couldn't mount them in the 35mm pipework could i ?
The pump that is their at the moment is controlled by both boilers and has an overrun of 5 minutes could i link the valves with the pump wiring so they close
when the pump stops ?
Or i put the check valves inbetween the boilers on the flow and return and put a bigger pump where the alpha is at the moment and we could possibly use the alpha as a shunt.
As I said it would be better to fit one pump per boiler with a non return valve on the return. Then the sequencer will be able to properly control the boilers so that just one can work without the pump still sending half of the flow through the off boiler.
Fitting a spring return motor valve to the return connection to each boiler would achieve the same result but enable a single pump to be used. But we think your pump is undersized already so thats not a recommended option. Furthermore the valve would need to be connected so that it remains open for the pump over run period.
Tony
Fitting a spring return motor valve to the return connection to each boiler would achieve the same result but enable a single pump to be used. But we think your pump is undersized already so thats not a recommended option. Furthermore the valve would need to be connected so that it remains open for the pump over run period.
Tony
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