Should I get a combi or keep the cylinder?

It comes down to simultaneous demand. One bathroom, and a combi is simpler and frees a cupboard. Two or more bathrooms likely to be used at the same time, and stored hot water from a cylinder serves them far better, because a combi shares one flow rate between every outlet. Mains flow rate at the kitchen tap is the other deciding measurement.

Can the new boiler go where the old one was?

Often, and it is usually cheaper if it can, but it is not automatic. The flue has to meet current clearance distances from windows, doors and boundaries, which have changed over the years, and the condensate needs a route to a drain. Sometimes a boiler that was legal in 2006 sits in a position that is no longer allowed.

Why does the gas pipe need upsizing?

Because a modern boiler often has a higher input than the appliance it replaces, and a 15mm tail cannot deliver the volume over any distance without the pressure dropping below the permitted working range. Upsizing the run from the meter to 22mm fixes it. How much of that run is accessible is what makes it cheap or expensive.

How long does a boiler swap take?

A straight swap in the same position, with no gas upsizing and an easy condensate route, is typically a day. Moving the boiler, upsizing the gas, converting from a cylinder to a combi or removing loft tanks takes two days or more. We tell you which it is after the survey rather than on the morning.

What happens to the old cylinder and tanks?

If you move to a combi they come out, and the airing cupboard and loft space come back, but the pipework they served has to be properly capped and the loft boards and insulation made good. That work is in the quote rather than a surprise. If you keep stored hot water, the cylinder is assessed and often replaced at the same time.

New Boiler Installation
In London

A boiler is specified by the building, not chosen from a list. Two houses on one street take different boilers: one has a bathroom mid-plan, the other an outside wall at every fitting.

Flue route surveyed first
Gas pipe size checked
Condensate drain planned

Quick Quote Online Call 07401 062636

Excellent5.07 reviews

Reviews

What Customers Say About The Work

Excellent5.07 reviews

Really pleased with the service from Drain Plumb Contractors. The work was carried out professionally, everything was explained clearly, and the area was left clean and tidy afterwards. Would happily recommend them to anyone looking for a reliable plumber.
Google reviewer
Had an urgent plumbing problem and needed someone to help. Drain Plumb Contractors were professional and helpful throughout, and the issue was dealt with efficiently. A stressful situation made much easier. Thank you for the great service.
Google reviewer
Great service for a drainage problem that needed sorting. The team were helpful, explained what needed doing and handled the job professionally. Everything was left in good order afterwards. I'd definitely consider using Drain Plumb Contractors again.
Google reviewer
Really good experience from start to finish. Friendly, professional and easy to deal with, with clear communication throughout. It's reassuring to find tradespeople who take the time to explain the work and treat your property with care. Would recommend.
Google reviewer
Very happy with the service provided. Communication was clear, the work was explained before getting started, and the whole process was straightforward. Good workmanship and a professional approach. I'd be happy to use Drain Plumb Contractors for future work.
Google reviewer
Very pleased with the plumbing work. The job was completed to a good standard, and the attention to detail was appreciated. Everything was left neat and tidy, and the service was professional throughout. Would happily recommend them.
Google reviewer
I've been very happy with the service from Drain Plumb Contractors. They're professional, approachable and take the time to explain things properly. It's good to have a company you can contact when plumbing or drainage work is needed. Would recommend them to others.
Google reviewer

Flue Route
Where the flue can exit is the first thing that limits where a boiler goes.
Gas Supply
The incoming gas pipe has to carry what the new boiler draws.
Condensate
A condensing boiler needs a drain for its condensate, planned in advance.
Specified, Then Priced
The boiler type follows the survey, and the written price follows that.

A boiler flue terminal and condensate pipe on the outside wall of a British house

Boiler Installation

Combi, system or regular

A combi heats water on demand and needs no cylinder or tank, which is why it suits flats and smaller houses. Its limit is simultaneous demand: one shower is fine, two at once is not, because flow rate is shared. A system boiler keeps a hot water cylinder, which gives you stored hot water that several outlets can draw at once, and wants a cupboard for it. A regular boiler keeps a cylinder and the loft tanks, and is normally the answer where the existing pipework or a gravity fed shower makes removing the tanks expensive.

The decision is driven by two numbers: how many bathrooms are likely to run together, and what the incoming mains flow rate actually measures at the kitchen tap.

Boiler Installation is priced after the job has been seen, anywhere in the areas we cover. Send the postcode and a few lines about what it is doing when you contact us, and the answer comes back in writing.

Quick Quote Online

The Job In Detail

What Boiler Installation Involves

The three things the survey finds

Flue route first. A flue has to terminate a set distance from windows, doors, boundaries and openings, and in a terrace that often decides which wall, or whether a vertical flue through the roof is the only legal option.

Gas pipe size second. A new boiler frequently has a higher input than the one it replaces, and the existing 15mm gas tail will not carry it. Upsizing to 22mm from the meter is common, and the length of that run is a real cost that nobody can guess from a photograph.

Condensate third. A condensing boiler produces acidic water continuously and it has to reach a drain with a fall all the way and no external run that can freeze. In a flat with no accessible waste, this is sometimes the hardest item on the list.

What we put in writing

The boiler type and output with the reason for it, the flue route, any gas pipe upsizing, the condensate route, what happens to the old cylinder or tanks, the system cleaning and inhibitor, and the commissioning and registration paperwork. Priced as one job so there is nothing to discover on the day.

Quick Quote Online

How It Works

How A Boiler Installation Job Runs

Send the old boiler

A photo of it, where it sits in the house and where its flue comes out.

Survey the three limits

Flue route, gas pipe capacity and condensate drainage are checked on site.

A specified quote

The boiler, the work around it and the price, written down before anything is ordered.

Old boiler on its way out? Send a photo of it and of where the flue exits.

Price A New Boiler

FAQs

Boiler Installation Questions

It comes down to simultaneous demand. One bathroom, and a combi is simpler and frees a cupboard. Two or more bathrooms likely to be used at the same time, and stored hot water from a cylinder serves them far better, because a combi shares one flow rate between every outlet. Mains flow rate at the kitchen tap is the other deciding measurement.
Often, and it is usually cheaper if it can, but it is not automatic. The flue has to meet current clearance distances from windows, doors and boundaries, which have changed over the years, and the condensate needs a route to a drain. Sometimes a boiler that was legal in 2006 sits in a position that is no longer allowed.
Because a modern boiler often has a higher input than the appliance it replaces, and a 15mm tail cannot deliver the volume over any distance without the pressure dropping below the permitted working range. Upsizing the run from the meter to 22mm fixes it. How much of that run is accessible is what makes it cheap or expensive.
A straight swap in the same position, with no gas upsizing and an easy condensate route, is typically a day. Moving the boiler, upsizing the gas, converting from a cylinder to a combi or removing loft tanks takes two days or more. We tell you which it is after the survey rather than on the morning.
If you move to a combi they come out, and the airing cupboard and loft space come back, but the pipework they served has to be properly capped and the loft boards and insulation made good. That work is in the quote rather than a surprise. If you keep stored hot water, the cylinder is assessed and often replaced at the same time.

Boiler Installation

Replacing
Your Boiler?

Tell us the make and age of the current boiler, where it sits and how many bathrooms it serves. Photos of the boiler and the flue help most.

Excellent5.07 reviews

07401 062636

info@drainplumbcontractors.co.uk

Greater London

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New Boiler Installation
In London

Reviews

What Customers Say About The Work

Flue Route

Gas Supply

Condensate

Specified, Then Priced

Boiler Installation

Combi, system or regular

The Job In Detail