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Discuss Will a new Combi boiler improve shower flow?? in the Plumbing Forum area at PlumbersForums.net

Jkb

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As the title says. I have been going round in circles deciding what to buy or get fitted (with a raft of various advice)...the short story (so far).

I have an old Combi boiler needs replacing and, I am having a new bathroom installed in October but, I want to improve the all round shower flow in my house. I have 2 upstairs thermostat mixer showers, the hot flow on one is 2l per minute and the other is 6l per minute, (not great I know). Both shower flows were measured by me with the thermostat turned to hot water only on both at the same time and, a measuring jug (probably not massively accurate but the best I can do for now). My Combi boiler is downstairs almost directly underneath both showers.

So, the house cold input is 16l per minute, again measured at the kitchen sink with a jug so around half of that is currently heating up for use by both showers, if they are on at the same time. I had thought that a Worcester highflow 550 Cdi with its 25l per minute hot output and its internal 50l tank were right up my street and, an ideal replacement but... not so. It would appear that my showers flow will not improve one jot, I’ll just have a good boiler with plenty hot water to call on but the water won’t get anywhere any quicker than it currently is. I’ve had 2 independent people keen to sell me this boiler but a third person now pops up stating all of the above and, recommending a pump in the attic to improve shower flow.. now I am none the wiser, I feel like I am back to square one.
any advice would be appreciated.

Cheers

J
 

Rob Foster

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Showers are really supposed to save households water but anyway. You need to test your water at 2 specific times .
7.00am Sunday when it should be at peak and then at same time or a bit later weekdays when demand is at maximum and test it at the outside tap.
You also need to explore the relationship between pressure and volume. Oversized combis just to produce your desired result are not the way fwds..a system boiler with a pressurised cylinder is the way you need to go...however micky mouse heating outfits will avoid telling you about them because they are not competant or qualified to fit them. From the horses mouth...Rob Foster aka centralheatking...and Wb are uck nowadays by the way
 

CBW1982

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GSR
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As per Rob above - best with an unvented cylinder if you want to improve overall flow to x2 showers.
 

YorkshireDave

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As the title says. I have been going round in circles deciding what to buy or get fitted (with a raft of various advice)...the short story (so far).

I have an old Combi boiler needs replacing and, I am having a new bathroom installed in October but, I want to improve the all round shower flow in my house. I have 2 upstairs thermostat mixer showers, the hot flow on one is 2l per minute and the other is 6l per minute, (not great I know). Both shower flows were measured by me with the thermostat turned to hot water only on both at the same time and, a measuring jug (probably not massively accurate but the best I can do for now). My Combi boiler is downstairs almost directly underneath both showers.

So, the house cold input is 16l per minute, again measured at the kitchen sink with a jug so around half of that is currently heating up for use by both showers, if they are on at the same time. I had thought that a Worcester highflow 550 Cdi with its 25l per minute hot output and its internal 50l tank were right up my street and, an ideal replacement but... not so. It would appear that my showers flow will not improve one jot, I’ll just have a good boiler with plenty hot water to call on but the water won’t get anywhere any quicker than it currently is. I’ve had 2 independent people keen to sell me this boiler but a third person now pops up stating all of the above and, recommending a pump in the attic to improve shower flow.. now I am none the wiser, I feel like I am back to square one.
any advice would be appreciated.

Cheers

J
Agree with the chaps, but there is something else you need to consider.

I can virtually guarantee that your existing pipework's ability to deliver is severely restricted through the fitting of poor quality ball valves or gates valves. Regardless of the way you go, it is vital that you get your plumber to remove as many impediments to flow as possible. At the end of the day, your whole system can be severely compromised by the inadvertent use of a single flow restriction. No matter how much money you throw at it it will only ever be as good as the poorest restriction to flow that 's in the circuit.
 

bogrodder

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You need to have your incoming main tested for dynamic pressure, before you consider an unvented cylinder, as they require a minimum.
 
OP
J

Jkb

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Agree with the chaps, but there is something else you need to consider.

I can virtually guarantee that your existing pipework's ability to deliver is severely restricted through the fitting of poor quality ball valves or gates valves. Regardless of the way you go, it is vital that you get your plumber to remove as many impediments to flow as possible. At the end of the day, your whole system can be severely compromised by the inadvertent use of a single flow restriction. No matter how much money you throw at it it will only ever be as good as the poorest restriction to flow that 's in the circuit.
Ok, thankfully all the pipe work is fairly well exposed and all quite close to the boiler/showers
 

YorkshireDave

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Ok, thankfully all the pipe work is fairly well exposed and all quite close to the boiler/showers
Think the phrase you were searching for is, "Thank you for that advice Dave." #MannersMakethMan :rolleyes:
 

Rob Foster

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Yes, sorry you are absolutely right. Thanks for your steer, i am sure I will be asking for more info in the near future :)
we will be here as always, the best independant plumbing and heating advice in the Uk and beyond and we are free
Rob Foster aka centralheatking
 
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J

Jkb

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Thank you JKB ;):)

No bother.

So, to ask the question, how much would fitting a new Combi boiler and unvented cylinder cost me? I know there are many variables with make/model/quality/pipework required etc... but let’s just say bog standard stuff to get two showers working better... I have approx £4.5k to spend, would that do?
 

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