New combi boiler in a cleared airing cupboard after a conversion

Combi conversions · System and tanks to combi

Convert to a combi boiler in Andover

Old loft tanks and hot water cylinder out, a modern combi in. The conversion is included in your online price.

Price my conversion 07774 319391

5.0 on Google from 63 reviews · Gas Safe and OFTEC registered

How much does it cost to convert to a combi boiler?

A combi conversion from DWM starts from £3,513, fitted and including VAT. Pick "Convert to a combi" in the price tool and the conversion is built into the estimated price you see.

Call 07774 319391 or WhatsApp Dexter.

Price

From £3,513 fitted, including VAT

The conversion is added automatically when you pick "Convert to a combi" in the price tool.

Price my conversion

What affects the price

Where the new combi will go
How much pipework needs rerouting
Removing a back boiler or warm air unit
The size of the combi your home needs

How long it takes. A conversion usually takes longer than a straight swap, often two to three days. Dexter confirms the timing with your price.

Before: old boiler removed and the cupboard cleared for a conversion, a DWM job in the Andover area — Before: old boiler removed and the cupboard cleared for a conversion

About this job

Changing an older system to a combi is the job Dexter does most. A conversion takes out the hot water cylinder, the cold water tank and the feed and expansion tank in the loft, caps or reroutes the old pipework, and replaces the old boiler with a combi that heats water on demand.

The result is hot water at mains pressure, a free airing cupboard and an empty loft space, with no tanks to freeze, leak or fill up with sludge. Dexter converts system boilers, gravity fed systems and warm air heating to combi boilers, and the reviews below describe several of these jobs in customers' own words.

A combi is not right for every home. If you have several bathrooms used at the same time or low mains pressure, Dexter will say so and suggest a system boiler with an unvented cylinder instead.

Before: old tanks and vented cylinder, ready to come out, a DWM job in the Andover area — Before: old tanks and vented cylinder, ready to come out

What a combi conversion includes

Old boiler, cylinder and loft tanks removed
Redundant pipework removed or capped
New combi boiler fitted and commissioned
Chemical system flush and magnetic filter
Inhibitor and a programmable room thermostat
Manufacturer warranty registered for you
Building Control certificate

Why convert to a combi

Hot water at mains pressure, straight from the tap
No loft tanks to freeze, leak or need cleaning out
The airing cupboard freed up for storage
No waiting for a cylinder to heat up
Fewer parts in the system to go wrong

How it works

No call centre and no sales visit. The person you speak to is the person who does the job.

1Choose "Convert to a combi"
Answer a few questions in the price tool and the conversion is included in the estimated price.
2Layout checked
Dexter confirms where the combi will go and which pipework and tanks come out.
3Converted and commissioned
Tanks and cylinder removed, the combi fitted and tested, and the warranty registered for you.

Dexter's own photos

Real jobs, photographed by Dexter. No stock pictures.

Cupboard stripped back for a combi conversion
Before: an old vented hot water cylinder
After: a new Ideal boiler following a system conversion
Vaillant ecoTEC with a DWM badge in a brick garage

What customers say

5.0 on Google from 63 reviews. Read them all on Google

★★★★★

Dexter replaced our old vented heating system and hot water cylinder with a new combi in our loft, including a new gas run from our garage. Dexter is extremely polite, tidy and his work is first class. Turned up on time and worked hard to finish the job on schedule. I will certainly be using Dexter again and I would highly recommend DWM Plumbing & Heating.

Dean ChappellGoogle review, April 2025

★★★★★
Dexter replaced our old gravity fed water system with a new combi boiler, including removing the old pipes, header tank and cistern. Also fitted our new shower. He did a great job. Very polite and professional. Would absolutely recommend.
Nick SmithGoogle review, November 2024
★★★★★
Fitted a new unvented cylinder. Removed our very old failing vented system and re-routed pipework accordingly. Cleared out the old system and left the place very tidy each day. Ensured the work fitted to my schedule and even left us with availability of hot water (via the immersion) throughout the work. ...
Philip EwenGoogle review, August 2024
★★★★★
Dexter came and swapped our old boiler for a new Ideal one. Friendly, professional and worked hard over three days. Tidied everything up afterwards and we would definitely use his services again. Thanks very much.
Alex ReidGoogle review, August 2023

Questions

Combi conversions:
your questions

Not sure what boiler you have? Send Dexter a photo and he will tell you.

WhatsApp Dexter

Can any system be converted to a combi?

Most can, including system boilers, gravity fed systems and warm air heating. Homes with very high hot water demand or low mains pressure may be better on a system boiler, and Dexter will advise.

Will my water pressure be good enough?

A combi relies on your mains pressure and flow. Dexter checks these before the conversion so you know what to expect.

What happens to the loft tanks?

They are drained and removed along with the old pipework, or capped where removal is not practical.

Is the conversion in the online price?

Yes. Pick "Convert to a combi" in the boiler price tool and the conversion is included in the estimated price.

Ask Dexter about combi conversions

Send the short form and Dexter rings you back himself. Or call 07774 319391 or send a WhatsApp.

Gas Safe and OFTEC registered · 5.0 on Google from 63 reviews · Based in Andover, covering Hampshire and Wiltshire