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Just bolt on a pump or power shower(s), easier all round.
I tried this originally I installed a pump for I think £300. It was so noisy and it lasted 1 year before it broke. It now sits unplugged. Redundant
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If I go back to your first post, you believe that your incomming flow rate is around 15 litres per minute. Any Combi fitted should be sized to that flow rate. A 42kw Combi requires a much higher flow rate than that.

You have clearly set out what your requirements are - you need a decent heating engineer to design a system to deliver them and give you some guarantees.

A Combi solution (without an accumulator) winot address the fundamental issue that you have - low flow.


At the moment, with the route you are following, the likely outcome is that the showers won’t perform significantly better than they do now.

I would also talk to your neighbours as to how they have addressed and resolved this issue.

Apologies, but I have seen it so many times - systems ripped out, an enormous Combi on the kitchen wall - and the shower still trickles.

As the previous poster succinctly said - pumping the shower from a vented hot water tank will at least show some imorovement.
That’s fine. Appreciate being told the facts. Thinking now that I agree that flow rate and pressure is going to determine setup. Not just wacking I’m a big system without decent flow rate. I Just don’t understand why 2 separate plumbers came and recommended a combi. I guess finding a plumber who’s thorough and very competent is the next step. Any recommendations for one who works in Northampton please let me know
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The other dynamic to consider is ...you install pump assistance to achieve desired rate from your combi then as you are legitimately taking your neighbours water they go and get
similar pumps installed and you are all back to square one. I watched a whole cul de sac in
Hightown go this way we did our fair share. Stored water is the best way it can build up overnight for the morning onslaught and recover during the day. Then in the summer you will be laughing when your neighbours cant even suck it out of the main
centralheatking
That explains a lot. As a general member of society it didn’t enter my mind that the mains coming into my house ever varies and or wouldn’t be sufficient to run any size powershowers. Without thinking it through I just expected a limitless flow rate from the outside main pipe. I always thought that people stored water in cylinders primarily because the boiler was unable to produce enough hot water on demand. And not that the incoming cold supply may not be able to keep up.
 

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gmartine

Gas Engineer
I tried this originally I installed a pump for I think £300. It was so noisy and it lasted 1 year before it broke. It now sits unplugged. Redundant
Looking at that install I'm not surprised...no insulation (for pipes or pump), pipes insufficiently clipped and poorly installed, unsuitable pump location ( right next to cupboard door). Was it even screwed down or did it just bounce around on it 's rubber feet while knocking the outlet pipes on that dividing wall? Anyhow there are better ways and much much longer lasting and quieter pumps say by StuartTurner or Grundfos so perhaps you should revisit the idea.
 
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I tried this originally I installed a pump for I think £300. It was so noisy and it lasted 1 year before it broke. It now sits unplugged. Redundant
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That’s fine. Appreciate being told the facts. Thinking now that I agree that flow rate and pressure is going to determine setup. Not just wacking I’m a big system without decent flow rate. I Just don’t understand why 2 separate plumbers came and recommended a combi. I guess finding a plumber who’s thorough and very competent is the next step. Any recommendations for one who works in Northampton please let me know
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That explains a lot. As a general member of society it didn’t enter my mind that the mains coming into my house ever varies and or wouldn’t be sufficient to run any size powershowers. Without thinking it through I just expected a limitless flow rate from the outside main pipe. I always thought that people stored water in cylinders primarily because the boiler was unable to produce enough hot water on demand. And not that the incoming cold supply may not be able to keep up.
There is a wealth of experience on PF, we do not always agree on everything, I think you are getting the picture now. Combi Boilers are smashing for the correct circumstances and an absolute inadequate bind in unappropriate usage. centralheatking
 
We cover a number of properties in Rushden - if that is close to you.
I live approximately 18 miles away/30 min drive from Rushden. However I would have a preference to someone local to Northampton if possible.
Would anyone recommend using sites like mybuilder to find someone? The purpose isn’t to find someone to undercut someone, cost is secondary to achieving a good result . Just someone who is has a good local reputation and will be accountable
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Looking at that install I'm not surprised...no insulation (for pipes or pump), pipes insufficiently clipped and poorly installed, unsuitable pump location ( right next to cupboard door). Was it even screwed down or did it just bounce around on it 's rubber feet while knocking the outlet pipes on that dividing wall? Anyhow there are better ways and much much longer lasting and quieter pumps say by StuartTurner or Grundfos so perhaps you should revisit the idea.
It wasn’t clipped down. Want pressurised hot and cold now for mixer taps . So vented boiler system is defo not an option. And would like to avoid Standalone pumps
 
To anyone still following this
Managed to get Anglian water round to check my outside feed. Which is surprisingly good.

Outside Mains
3.9 bar
50ltrs/min He was using a Weir cup (Googled the name) which seems optimistically high

Back tap approx 15 m ish away from mains
3.5 bar
25 ltrs per min
So it’s lost half of the flow

I then run a jug test myself running each cold tap on full and putting a jug under for 6 seconds. Multiply x10 for ltrs/min

1200ml /12ltrs kitchen tap

1500ml /15 ltrs Bath

2800ml / 28ltrs sink tap upstairs

For some reason the kitchen tap is terrible. And the bath cold feed appears to coming from the tank upstairs. Not the outside supply.

My questions are:
  1. how much loss is normally expected between mains and house?
  2. If I install a 22mm cold pipe to feed new boiler. what start point do I ask him to attach it at in order to loose the least flow.
  3. Any rules of thumb of how much loss in flow will there generally be going from ground level to floor 1 of a house in the 22mm pipe.
  4. Based on the fact I have an existing gravity heating system working. Could I install the new water pipe. Check the pressure and flow. And then buy according to what I actually get?
  5. Would digging a new 32mm supply to the mains be overkill. Looking at prices. It seems approx 1k ish. Which is what any accumulators might cost and would mean It wouldn’t take any space up in the house. And should mean I’m always gonna be in a good supply of water.
 
To anyone still following this
Managed to get Anglian water round to check my outside feed. Which is surprisingly good.

Outside Mains
3.9 bar
50ltrs/min He was using a Weir cup (Googled the name) which seems optimistically high

Back tap approx 15 m ish away from mains
3.5 bar
25 ltrs per min
So it’s lost half of the flow

I then run a jug test myself running each cold tap on full and putting a jug under for 6 seconds. Multiply x10 for ltrs/min

1200ml /12ltrs kitchen tap

1500ml /15 ltrs Bath

2800ml / 28ltrs sink tap upstairs

For some reason the kitchen tap is terrible. And the bath cold feed appears to coming from the tank upstairs. Not the outside supply.

My questions are:
  1. how much loss is normally expected between mains and house?
  2. If I install a 22mm cold pipe to feed new boiler. what start point do I ask him to attach it at in order to loose the least flow.
  3. Any rules of thumb of how much loss in flow will there generally be going from ground level to floor 1 of a house in the 22mm pipe.
  4. Based on the fact I have an existing gravity heating system working. Could I install the new water pipe. Check the pressure and flow. And then buy according to what I actually get?
  5. Would digging a new 32mm supply to the mains be overkill. Looking at prices. It seems approx 1k ish. Which is what any accumulators might cost and would mean It wouldn’t take any space up in the house. And should mean I’m always gonna be in a good supply of water.
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
 

garygvl

Gas Engineer
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
£1000 not 1kilometre
 

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
 
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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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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Post automatically merged:


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?
Post automatically merged:


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.
 
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
 

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