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ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
Did he test from your stop tap / there supply

Kitchen tap could have flow restrictors installed

All depends on what pipe you have coming in
Best option is either a 25mm or 32mm alk that will give you the best flow rates off there figures

If your going for a Combi Boiler tbh no point upgrading as the max you will require is around 14lpm so 15mm supply close by

Depends on pipe size and bends etc pulled bends / benders restrict less than an elbow eg soldered if you can’t get around use swept bends

Yes you could get the new main installed and then make the decision based on real world figures etc

No as you can always reduce the flow and pressure can’t always increase it easily also depends on what there supply is (water board to the meter / stop tap) as if it’s 20mm not worth upgrading to a 32mm etc
 

Brambles

Advent Win
If you go down the large combi route, for a Vailliant 938, you will need 24 lpm at the point of entry into the boiler to achieve full utilisation.

Apologies for being a nerd, but we have worked extensively with these type of boilers (installed in properties by mistake) in North London matching them with pump accumulators to improve shower performance.
 
Did he test from your stop tap / there supply

Kitchen tap could have flow restrictors installed

All depends on what pipe you have coming in
Best option is either a 25mm or 32mm alk that will give you the best flow rates off there figures

If your going for a Combi Boiler tbh no point upgrading as the max you will require is around 14lpm so 15mm supply close by

Depends on pipe size and bends etc pulled bends / benders restrict less than an elbow eg soldered if you can’t get around use swept bends

Yes you could get the new main installed and then make the decision based on real world figures etc

No as you can always reduce the flow and pressure can’t always increase it easily also depends on what there supply is (water board to the meter / stop tap) as if it’s 20mm not worth upgrading to a 32mm etc

Anglian water tested from the mains 50l

And then I asked Anglian water to test from my outside back tap. Which is off from my stop tap directly on the other side of the wall, under 1/2 meter away. 25ltrs flow approx

Interestingly non of the heating guys have tested my water pressure. Just told me it’s good

So Leaving out the idea of moleing a new pipe to my mains for now.

In The last visit I had the heating engineer said there was no point upgrading internal feed to a 22mm pipe. As my pipe work coming in was smaller and stepping up after a smaller pipe coming in wouldn’t achieve anything . He could only see this pipe as pictured. Is unlikely this pipe is any larger below this cupboard? Is this likely to be the same size all the way to my mains is what I’m asking?
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If you go down the large combi route, for a Vailliant 938, you will need 24 lpm at the point of entry into the boiler to achieve full utilisation.

Apologies for being a nerd, but we have worked extensively with these type of boilers (installed in properties by mistake) in North London matching them with pump accumulators to improve shower performance.
this in my head at the mo is my most likely option. If I can achieve 25ltrs feed to my airing cupboard upstairs. Then I’m thinking to put the largest combi that’l physical fit in the cupboard. I think the one you mentioned is a storage combi, so maybe one of those. To give me the best output.

the other option. Is still the unvented in the loft. But I’m worried about the weight of it up there and would spend a lot upgrading the rafters and using crossbeams brackets etc to spread the load across the whole of the roof rafters. Before I’d feel comfortable sticking up the unvented. Also. I need a hand rail everywhere and probably better lighting and maybe rafter insulation
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PF never forgets anybody...Dan does That..
Is your area rural or built up suburban ?
1. these figures .great in both departments ..your figures are a flow most london people would kill for. It was also good to get your utility out as well normally they are quite reticent.
2. You cannot loose out with a new supply to your gaff from the meter/utility stop...but is it really 1km ?...perhaps its 1metre.
3. so your analysis 4 & 5 is valid
let us know...you are tenacious ...quite right too. centralheatking
I live in a suburban area. New built (ish) 2000 aged property detached.
Hoping to try and install pipe work and get away without installing a new feed to Mains (yeah I meant £1000 ish cost). If I can achieve 20ltrs plus to any boiler system, this should be enough to run and shower and wash up at the same time without a dramatic loss of flow?
 

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ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
I would say that’s unacceptable for what your purposing 15mm incoming/20mm alk won’t do a shower and washing up at the same time

Best way to test this

Open the outside tap then open the kitchen tap (cold) this will give you an idea
 
I would say that’s unacceptable for what your purposing 15mm incoming/20mm alk won’t do a shower and washing up at the same time

Best way to test this

Open the outside tap then open the kitchen tap (cold) this will give you an idea
sorry what is alk term?

the kitchen tap has flexi hoses feeding it that look even narrower, as a guess i'd estimate it uses like 10 litre per minute, maybe could restrict it slightly?

and a decent shower (i googled the answer)use 15-20 ltrs p/min? so if my incoming is to boiler and i put in a gigantic combi, 25 ltr/per min should this not be enough?

I will try you experiment of opening both taps when i finish work

do u think that it'l be 15mm pipework that run under that cupboard all the way to the mains? i'd rather up the water flow if possible and not be under powered, i will mole to the mains if i have to (price dependant) or go back to the unvented in loft, both may work out similar in price
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
sorry what is alk term?

the kitchen tap has flexi hoses feeding it that look even narrower, as a guess i'd estimate it uses like 10 litre per minute, maybe could restrict it slightly?

and a decent shower (i googled the answer)use 15-20 ltrs p/min? so if my incoming is to boiler and i put in a gigantic combi, 25 ltr/per min should this not be enough?

I will try you experiment of opening both taps when i finish work

do u think that it'l be 15mm pipework that run under that cupboard all the way to the mains? i'd rather up the water flow if possible and not be under powered, i will mole to the mains if i have to (price dependant) or go back to the unvented in loft, both may work out similar in price
Sorry 20mm blue alkathene pipe eg 20mm alk

By the time you take some restriction in and your figures are only with one tap open so could be only 5lpm out of one and 10 lpm out of another etc

No I think it will join to a blue alkathene pipe somewhere
 
Sorry 20mm blue alkathene pipe eg 20mm alk

By the time you take some restriction in and your figures are only with one tap open so could be only 5lpm out of one and 10 lpm out of another etc

No I think it will join to a blue alkathene pipe somewhere
so not the most scientific. But I’m standing in the garden. With my hand through the window. Put the sink on full. Then mid way through the video. Garden tap is running full belt. With no hose on it. Then I turn it garden tap back to closed. There’s maybe a 20% loss. Maybe I’m biased cos Id rather do the simple option 😂
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Sorry 20mm blue alkathene pipe eg 20mm alk

By the time you take some restriction in and your figures are only with one tap open so could be only 5lpm out of one and 10 lpm out of another etc

No I think it will join to a blue alkathene pipe somewhere
so not the most scientific. But I’m standing in the garden. With my hand through the window. Put the sink on full. Then mid way through the video. Garden tap is running full belt. With no hose on it. Then I turn it garden tap back to closed. There’s maybe a 20% loss. Maybe I’m biased cos Id rather do the simple option 😂
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so not the most scientific. But I’m standing in the garden. With my hand through the window. Put the sink on full. Then mid way through the video. Garden tap is running full belt. With no hose on it. Then I turn it garden tap back to closed. There’s maybe a 20% loss. Maybe I’m biased cos Id rather do the simple option 😂
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Got under the cabinet that’l be the blue 20 alk tube. You mentioned. If I connect a 20 or 22 mm feed straight on to that. That should give me as little loss of possible?
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so not the most scientific. But I’m standing in the garden. With my hand through the window. Put the sink on full. Then mid way through the video. Garden tap is running full belt. With no hose on it. Then I turn it garden tap back to closed. There’s maybe a 20% loss. Maybe I’m biased cos Id rather do the simple option 😂
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Got under the cabinet that’l be the blue 20 alk tube. You mentioned. If I connect a 20 or 22 mm feed straight on to that. That should give me as little loss of possible?
 

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centralheatking

Esteemed
Plumber
so not the most scientific. But I’m standing in the garden. With my hand through the window. Put the sink on full. Then mid way through the video. Garden tap is running full belt. With no hose on it. Then I turn it garden tap back to closed. There’s maybe a 20% loss. Maybe I’m biased cos Id rather do the simple option 😂
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Got under the cabinet that’l be the blue 20 alk tube. You mentioned. If I connect a 20 or 22 mm feed straight on to that. That should give me as little loss of possible?
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Got under the cabinet that’l be the blue 20 alk tube. You mentioned. If I connect a 20 or 22 mm feed straight on to that. That should give me as little loss of possible?
Pizzaboy I think you have all the info you need to make an informed decision, obviously your decision is cost and effort dependant. The facts and consequences of the alternatives are manifest. Let us know what you decide please and then mid summer before the school run
was it the best ? centralheatking
 
So i had a quote through for valliant 938 38kw storage combi, to be locaed in the airing cupboard on first floor and vertical flue coming out of roof)
quote is approx £4200 inc vat.
its has a small storage of 20ltr tank and i think can throw out 20lts/min, then 16 after small tank is drained. this should help when two taps are running for hand washing etc?

i have headed everyone's sage advise about the limitations of combis over unvented, but without converting my attic with structural floor supports and full flooring, i wouldn't want to put it in the attic and i dont have space to put the unvented cyclinder anywhere else.

they listed the job fully which is nice, i have also added on putting in a new 22 supply in from stop cock
though the alk pipe internally i think is 20mm internally (25mm external) so is stepping up to 22mm but would be better than the reguilar 15mm copper that woud currently go upstairs.

job is listed below :
Isolate water supplies and drain down heating system. Test gas supply. Disconnect pipe work from boiler. Remove boiler, flue and cylinder. Reconfigure pipe work to accommodate a combi boiler Connect power flush unit to heating circuit. Connect mains water to unit. Hard flush heating system Add FX2 acid to flushing unit and flush each radiator. Drain heating circuit. Re flush heating system with clean water. Add neutralising crystal to unit flush and drain. Remove flush unit from heating system. Supply and fit new high efficiency Vaillant 938 Ecotec + 38KW boiler in airing cupboard. Install new vertical flue from boiler through roof installing a weather slate. Connect heating pipe work to boiler. Run condensate pipe from boiler to drain. Connect hot and cold-water supplies to boiler. Run new 28mm gas pipe work from meter, through the loft and connect to boiler in the airing cupboard. Connect electrics to boiler. Connect existing room stat. Fill heating system adding pc 100 inhibitor. Test and commission whole heating system. Brick up old flue opening Register boiler with gas safe for building control certificate.
 

centralheatking

Esteemed
Plumber
So i had a quote through for valliant 938 38kw storage combi, to be locaed in the airing cupboard on first floor and vertical flue coming out of roof)
quote is approx £4200 inc vat.
its has a small storage of 20ltr tank and i think can throw out 20lts/min, then 16 after small tank is drained. this should help when two taps are running for hand washing etc?

i have headed everyone's sage advise about the limitations of combis over unvented, but without converting my attic with structural floor supports and full flooring, i wouldn't want to put it in the attic and i dont have space to put the unvented cyclinder anywhere else.

they listed the job fully which is nice, i have also added on putting in a new 22 supply in from stop cock
though the alk pipe internally i think is 20mm internally (25mm external) so is stepping up to 22mm but would be better than the reguilar 15mm copper that woud currently go upstairs.

job is listed below :
Isolate water supplies and drain down heating system. Test gas supply. Disconnect pipe work from boiler. Remove boiler, flue and cylinder. Reconfigure pipe work to accommodate a combi boiler Connect power flush unit to heating circuit. Connect mains water to unit. Hard flush heating system Add FX2 acid to flushing unit and flush each radiator. Drain heating circuit. Re flush heating system with clean water. Add neutralising crystal to unit flush and drain. Remove flush unit from heating system. Supply and fit new high efficiency Vaillant 938 Ecotec + 38KW boiler in airing cupboard. Install new vertical flue from boiler through roof installing a weather slate. Connect heating pipe work to boiler. Run condensate pipe from boiler to drain. Connect hot and cold-water supplies to boiler. Run new 28mm gas pipe work from meter, through the loft and connect to boiler in the airing cupboard. Connect electrics to boiler. Connect existing room stat. Fill heating system adding pc 100 inhibitor. Test and commission whole heating system. Brick up old flue opening Register boiler with gas safe for building control certificate.
nice one pizza boy so this is a full BG quotation not an estimate...I will look at it very
carefully ...as BG are a benchmark outfit...as we will all. more later chking
 
by bg do you mean british gas? the quote i got is from a local firm in northampton, not british gas? out the 3 local heating engineers i had round, they the first to come back to me with a price. i did an online estimate with boxt, but again would prefer someone local i can get back to do repairs, service, warranty etc
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centralheatking

Esteemed
Plumber
by bg do you mean british gas? the quote i got is from a local firm in northampton, not british gas? out the 3 local heating engineers i had round, they the first to come back to me with a price. i did an online estimate with boxt, but again would prefer someone local i can get back to do repairs, service, warranty etc
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get a quote and specification from BG , I would just to set a benchmark price, look at the
extra cover and interest free deal , I am by no means BG lover but it costs zero to get them around and they are desperate for new business. they will sell you a WB but with 10years on it who cares centralheatking
 
get a quote and specification from BG , I would just to set a benchmark price, look at the
extra cover and interest free deal , I am by no means BG lover but it costs zero to get them around and they are desperate for new business. they will sell you a WB but with 10years on it who cares centralheatking
thats a great idea, to give me a ball park figure and they shouldn't cut any corners on the install, cost was never primary over getting the correct setup which didn't feel underpowered and installed with correct with what i have from incoming mains.
i've just booked a video call quote with british gas, on friday, cheers.

also If anyone reading this has any positive, negative views towards storage combis, in particular the 938 valliant ecotec 38kw, please write a comment, thank you
 
Hello sorry if this is on going... I have come to decide on putting an unvented cyclinder in the airing cupboard, the british gas man said this one would fit in there and quoted me this:
Gledhill 180ltr StainlessLite Plus Unvented cylinder 1306h x 550dia

I had a question? Is there many negatives of not replacing the boiler and just fitting the unvented and making it work with the current old ideal boiler i have? I'm not trying to be cheap, its just i plan on combining the utility room into the garage in the future and until i do the work i don't want to guess the new permanent placement of the boiler, which will go somewhere in the garage based on where the new wall is. To fit a new boiler in old utility room and then move it again once the new room is done. seems like i may have to damage walls for new flues etc and if the old boiler is still working this can get me through until i do the conversion???
 

EvilDrPorkChop

Gas Engineer
Advent Win
Hello sorry if this is on going... I have come to decide on putting an unvented cyclinder in the airing cupboard, the british gas man said this one would fit in there and quoted me this:
Gledhill 180ltr StainlessLite Plus Unvented cylinder 1306h x 550dia

I had a question? Is there many negatives of not replacing the boiler and just fitting the unvented and making it work with the current old ideal boiler i have? I'm not trying to be cheap, its just i plan on combining the utility room into the garage in the future and until i do the work i don't want to guess the new permanent placement of the boiler, which will go somewhere in the garage based on where the new wall is. To fit a new boiler in old utility room and then move it again once the new room is done. seems like i may have to damage walls for new flues etc and if the old boiler is still working this can get me through until i do the conversion???
You will need a bigger cylinder than 180l. With family you will need at least a 200l, and I would recommend a 250l.

Nothing wrong with keeping your old boiler, you could make the system a sealed system when you do the cylinder with your existing boiler. Then all the tanks in the loft would go.
 
You will need a bigger cylinder than 180l. With family you will need at least a 200l, and I would recommend a 250l.

Nothing wrong with keeping your old boiler, you could make the system a sealed system when you do the cylinder with your existing boiler. Then all the tanks in the loft would go.
is there anything online. That lets you pickcylinders based on cupboard size and include space for the pipe work etc.

my cupboard internals are
650mm w
720 d
2370 h

aren’t all unvented sealed systems? Or are u referring to having an separate expansion vessel above the cylinder

we are 2 adults and 2 kids. So you think 200ltr is minimum then, I’m guessing il just pick the largest that will fit
 

gmartine

Gas Engineer
Looks like you got there in the end, did you keep your old boiler and what capacity is the cylinder you opted for?
 
Looks like you got there in the end, did you keep your old boiler and what capacity is the cylinder you opted for?
Mega flow 210i /capacity 195ltr. Was the largest that would fit the cupboard. I think.
Haven’t changed the boiler. As I’m still planning on doing the garage. The system works perfectly tho. So fingers crossed the boiler doesn’t die until I’m ready to move it
 

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