House Renovation - Conflicting Advice, Help please

[jonwestuk]

Hi

I am wondering if I can get some advice. I am in the process of renovating my 3 story terraced house, but am getting conflicting opinions from the 3 plumbers that I have had round to quote for the renovations. The current situation is fairly straight forward. I have a
- W/C with shower on the ground and top floor
- A kitchen with a dishwasher on the 1st Floor
- A utility room with a washing machine on the ground floor
- No option for further extension, roof conversion, so it is highly unlikely that the water demands will change.

The mains connection is a 15mm pipe and the flow rates are:

- Above 22 litres / minute from the ground floor cold water
- 10 litres / minute from the ground floor hot water*
- 19 litres /minute from the top floor cold water
- 10 litres /minute from the upstairs hot water*

*The current combi boiler is undersized for the house as it is a Worcester Bosch 25SI, and the flow rate has been restricted down to 10 litres a minute to ensure a consistent temperature. (Boiler installed by previous owner)

The current boiler meets my needs whilst it is just my wife and I living at the house, but when our family grows we are planning to upgrade the boiler to a larger boiler probably a 42. We are considering whether or not If the flow rate is too low to allow the use of showers at the same time, we may then also increase the size of the mains to the house to 32mm (I have already had a quote for this and the cost would be reasonable as the Mains is directly outside my property).

I am getting two conflicting views regarding the existing pipework.

The two views are as follows:

1. Replace the old 15mm pipes throughout the house with 22mm. Leave the old 15mm feeding the kitchen until it is renovated when I could then disconnect it. There is easy access to run 22mm upstairs so long as plastic is used.

2. Keep the existing 15mm cold water pipes. Run a 22mm hot water pipe from the combi to the downstairs bathroom and connect it to the old 15 mm hot water pipe that feeds the kitchen and top floor bathroom. Then if I do end up upgrading the mains supply, connect 3 spurs to the 32mm pipe. 1 to the boiler; 1 to the downstairs bathroom/utility room; and the last to the upstairs kitchen and bathroom. In that way the volume from the 32 mm pipe will be evenly shared out ensuring that all of the 15mm pipes have minimal drop-off in flow if other taps are used.

My questions are as follows:

1. With the existing volumes, do you think a new mains connection will be required?. With above 22 litres a minute from the 15mm mains it seems like I could easily run two showers at 11 litres per minute, which should be a perfectly good shower? (32mm is excessive as a replacement, but the water board surveyor suggested to go for 32mm as the cost difference is negligible.) My concern is that the street is just starting to see the last generation move out and a new generation move in. As a result I expect more people moving from tanks to direct water feeds and combi boilers, so the pressure may be impacted.
2. Should I get 22 mm pipes run throughout the house? Or do you think that the 2nd option should suffice?
3. Overall what would you do to ensure the long term success of the installation? Are there other things I should consider?

I want to get this right first time, as changing it after I have renovated the bathrooms is not an option. I also need to work out fairly quickly if I am going to put in a new mains connection, as I will be replacing the outside wall of my downstairs bathroom as part of the refurbishment, so it would make sense to dig a trench and get a Thames Water authorised plumber to lay the pipe and get Thames Water to make the connection whilst the front of the house is already open.

Thanks in advance for your help.

 

[DeletedUser]

Go unvented

 

[jonwestuk]

Go unvented

Thanks for the advice, but I have no space to put a tank in place so a Combi is my only option.

 

[ServiceNumpty]

Sorry half read it, but if your sticking with a combi, even a 42cdi, why would you upgrade to 22mm. It would take an age for hot water to reach the taps. You've got 22lpm flow on existing supply, which would be adequate.
If you're going unvented which you aren't then upgrade.

 

[Groovejet]

How much space have you in the loft??
Install an unvented system and put it in loft.

Also depends on your finances, as uyou will also have a gas pipe to run and associated pipework and controls.

If you want it doing right 1st time , you should go down unvented route.

20 l/min is the minimum cold main requirement for unvented cyl.

Increase size of the mains, 25mm is adaquate.......run a 22mm circ pipe and branch off to taps etc in 15mm throughout the house.

The boiler you have at present will probaly struggle with family use e.g w/mc on... shower on ...running tap its normal to see it fluctuate.

Last idea......
Get a floor standing storage combi???
Worcester do a decent model
https://www.worcester-bosch.co.uk/homeowner/boilers/gas-boilers/greenstar-highflow-440cdi

 

[jonwestuk]

Sorry half read it, but if your sticking with a combi, even a 42cdi, why would you upgrade to 22mm. It would take an age for hot water to reach the taps. You've got 22lpm flow on existing supply, which would be adequate.
If you're going unvented which you aren't then upgrade.

Great advice, nobody mentioned that, but it makes perfect sense. There is also no point in heating loads of water just to sit in the pipe!

Would you still upgrade the mains into to the house? It struck me that from a flow perspective the 15mm mains into the house would be the main bottleneck as the hot and cold water have a 15mm pipe each. Increasing the mains and spurring one 15mm to the combi and one to the cold water would increase the flow substantially. Am I wrong?

 

[jonwestuk]

How much space have you in the loft??
Install an unvented system and put it in loft.

Also depends on your finances, as uyou will also have a gas pipe to run and associated pipework and controls.

If you want it doing right 1st time , you should go down unvented route.

20 l/min is the minimum cold main requirement for unvented cyl.

Increase size of the mains, 25mm is adaquate.......run a 22mm circ pipe and branch off to taps etc in 15mm throughout the house.

The boiler you have at present will probaly struggle with family use e.g w/mc on... shower on ...running tap its normal to see it fluctuate.

Last idea......
Get a floor standing storage combi???
Worcester do a decent model
https://www.worcester-bosch.co.uk/homeowner/boilers/gas-boilers/greenstar-highflow-440cdi[/QUOTE]


All good advice. I did originally try and spec an unvented in a cupboard and loft. Unfortunately the loft does not have the height and the cupboards were too narrow. The only option would be to put it in a room, which to be honest was not an option.

I like the idea of the floor standing combi for the high flow rates so will put that on my design. With a flow rate of 20 ltrs/min on those combi boilers I will definitely uprate the water mains into the house, and uprate the gas pipe from the mains supply to the current combi so that it has enough juice.

I am also secretly hoping that in 5-7 years when I need to upgrade the boiler for the beast, they will be a bit more efficient and have better flows rates anyway.

 

[Agile]

No combi is going to operate two showers together!

An open pipe flow rate is pretty irrelevant!

You need to measure the dynamic flow rate! 22 li/min @ 1.0 bar is about the minimum and would operate two showers if supplied from an unvented cylinder.

If you have space for a floor mounted storage combi then you have space for an unvented!

A storage combi only gives a high flow rate for a few minutes until the store is depleted.

Any plumber who suggests increasing pipes to 22 mm does not understand the basics and should not be chosen for any work.

I do not like the idea of calling out plumbers to give you free advice on specifications. That should be paid for consultancy!

Tony Glazier

 

[virgilns]

If loft height is a restriction, you can get horizontal unvented cylindars...so only about 60cm high...

when I did mine, I put in 32mm MDPE mains from the street, 28 mm to the unvented and then took feeds from that to taps.

I now have Nigra falls from both showers (overhead and handheld at the same time), kitchen tap on and sink tap and barely perceibvable presure drop. Could not have asked for more....

Just trying to pursuade my brother in law now into an unvented over a combi boiler...never did understand the desire for combis...never had one and never will

 

[fluxeyfingers]

I have had several combi's in different places and hopefully will never have to put up with one again!

 

[jonwestuk]

I have had several combi's in different places and hopefully will never have to put up with one again!

Hmmm, not filling me with confidence then. The only consistent response I had from the three quotes was that there was no logical place to put either a vertical normal, vertical thin or horizontal unvented cylinder. If I really did want one I would have to alter the roof, which sounds a little bit extreme for what I want to achieve.

Think I will have to make do with a combi and hope that they develop significantly over the next few years, or hope that unvented cylinder options change to better suit my property.

What I might ask my plumbers to do is to stick some additional pipes up into the attic, but to leave them disconnected, so that I have the pipework available without having to rip out bathrooms and kitchens if things change.

 

[jonwestuk]

I do not like the idea of calling out plumbers to give you free advice on specifications. That should be paid for consultancy!
Tony Glazier

If you read my post, I called the plumbers to quote for the work, get to know them and naturally discuss the options and their suggestions. I initially started with 2 quotes but I had conflicting advice and the third (a recommendation from a friend) only added a small amount of clarity so I thought it worth asking you fine gentlemen.

I am not going to feel guilty about reviewing my options in terms of both tradesmen and solutions. Frankly, only a fool would make such big decisions and pay such large amounts of money based on a single opinion and quote.

 

[Dan Robinson]

Do't worry about Tony - he's a good egg, but does have some interesting opinions on how business should be run (as well as some odd ideas on certain installation options).

He is right though... no combi - Even the Atag Q51 isn't really going to do the job adequately.

Although (loathe though I am to suggest it) the Vaillant 937 might just about cope?


You are not going to be better off for waiting for combi's to improve efficiency - laws of physics are pretty much as they are always going to be.

 

[jonwestuk]

Do't worry about Tony - he's a good egg, but does have some interesting opinions on how business should be run (as well as some odd ideas on certain installation options).

He is right though... no combi - Even the Atag Q51 isn't really going to do the job adequately.

Although (loathe though I am to suggest it) the Vaillant 937 might just about cope?


You are not going to be better off for waiting for combi's to improve efficiency - laws of physics are pretty much as they are always going to be.

Thanks for the insight. I am slowly coming to the realisation regarding the Combi boilers.

That said, it is only two shower rooms, the second of which is on the ground floor away from the bedrooms so it will hardly ever be used at the same time as the other.

Thinking about it again, it is more likely that the 2nd floor shower will be used by multiple people in quick succession, in which case one can argue that on demand water could be an advantage. Having just stayed at my Dads we realised that with 5 of us getting up in the morning, without the booster turned on, we killed his large unvented cylinder leaving a cold shower for the last person.

 

[virgilns]

I have had several combi's in different places and hopefully will never have to put up with one again!

Hmmm, not filling me with confidence then. The only consistent response I had from the three quotes was that there was no logical place to put either a vertical normal, vertical thin or horizontal unvented cylinder. If I really did want one I would have to alter the roof, which sounds a little bit extreme for what I want to achieve.

Think I will have to make do with a combi and hope that they develop significantly over the next few years, or hope that unvented cylinder options change to better suit my property.

What I might ask my plumbers to do is to stick some additional pipes up into the attic, but to leave them disconnected, so that I have the pipework available without having to rip out bathrooms and kitchens if things change.

thats because they didn't want to fit one or possibly though you'd shy away from the extra price??

ANYTHING is possible it just depends on how much you want it and how much you're prepared to pay. I'd wager any of the Dans or Agiles in here could fit one in your attic. unless you actually have a flat roof that is! weight could be a killer if you have thin balsa wood joists…space? i really can't see how.