Boiler Replacement Guide | Straight Swap, Move or Change Boiler Type

Quick Guide Summary

When should I keep my replacement boiler in the same location, move it or change boiler type?

If you are replacing your boiler, an important consideration is whether to keep your boiler type in the same location, move to a new location or change to a new boiler type altogether. There are three main types of boiler replacement: straight swaps, boiler moves and boiler changes. We explain each and advise when the circumstances are right for a straight swap, for moving your boiler and/or changing your boiler type.

Straight Swaps

keeping the same boiler type in the same location

Boiler Moves

moving the boiler but keeping the same boiler type

Boiler Changes

changing the boiler type - in the same or new location

How to use this Guide

When to stick with the same location

when to move the boiler

when to change boiler type

Boiler swaps - keeping the same boiler in the same location

If you have an existing combi, regular or system boiler and you are happy with its performance then the most straight forward option is to retain that system and boiler in its original location.

There may still be some upgrades required. For example, new condensing boilers will need a ‘condense pipe’ run from the boiler to a drain (internal or external). Combi boilers over 18kW will require a 22mm gas pipe. If your existing gas pipe is 15mm it will need to be re-run.

Advantages of a Boiler Swap

  • Cost effective
  • Quick – likely to be done in a day

Disadvantages of a Boiler Swap

  • If the boiler takes up cupboard space, is on show or is in an awkward location this does not change
  • For regular boilers, the generous manufacture’s warranties now available will only cover the boiler. All other components (pumps, valves, hot water cylinder) will be subject to future repair and replacement costs

Boiler moves - moving the boiler but keeping the same boiler type

Boiler moves are largely motivated by a desire to free up space, usually a kitchen cupboard, airing cupboard or bedroom wardrobe or by home extension plans.

The roof space is a popular choice of new location.

Whilst the boiler type is staying the same, which means the system components can stay the same, most of the boiler pipework will be new. The installer will need to run a new ‘condense pipe’ run from the boiler to a drain (internal or external) and probably a new, larger gas pipe, particularly if the distance from meter to boiler has increased.

Advantages of a boiler move

  • Frees up space

Disadvantages of a boiler move

  • Installation cost will be more as the fitting time is 1.5 – 2.5 days instead of one day for a ‘boiler swap’ in the same location.
  • For regular boilers, the generous manufacture’s warranties now available will only cover the boiler. All other components (pumps, valves, hot water cylinder) will be subject to future repair and replacement costs

Boiler change - changing the boiler type - in the same or new location

If your circumstances change, for example you extend your property and add more bathrooms, or you just want to move from a hot water tank to instantaneous hot water, then consider changing your boiler type. The most common changes are as outlined below:

Regular Boiler to Combi Boiler

Combi Boiler to System Boiler

Regular Boiler to System Boiler

Upgrading your Back Boiler

Regular Boiler to Combi boiler

If you would like to switch from stored hot water to hot water produced instantly by the boiler, then consider changing to a combi boiler system.

This will involve removing the hot water cylinder and tanks in the loft and replacing with a single combi boiler.

Advantages

  • Frees up space
  • You will have lower maintenance costs as heating and hot water functions are integral to the boiler and covered by the manufacturer’s warranty
  • Instant hot water

Disadvantages

  • Avoid if you have poor water pressure or flow rates
  • Avoid if you have three or more bathrooms – consider a system boiler
  • Avoid if you have old radiators and pipework
  • More expensive than a boiler swap as it will likely take 2-3 days

Combination Boiler to System Boiler

You would probably only consider this system change if you are extending your property and adding bathrooms.

The hot water flow rates on even the biggest combi boilers are reduced when there are multiple bathrooms and hot water taps in use at the same time. Providing you have good water pressure, a system boiler will deliver good hot water flow rates simultaneously to multiple hot water outlets.

It will involve installing a new steel hot water tank.

Advantages

  • Better hot water flow rates to multiple outlets than a single combi boiler
  • Great if you have multiple bathrooms
  • Economic if done as part of wider renovation works

Disadvantages

  • Expensive as a stand-alone job (i.e. not done as part of an house extension)
  • Will be more space consuming

Regular Boiler to System Boiler

If you are keeping your heat only (regular) boiler, then it is worth considering installing a system boiler instead of another regular boiler.

This will often involve moving from an ‘open-vent’ system to a sealed system. It will always involve changing your copper hot water cylinder to a steel, pressurised hot water cylinder.

Advantages

  • You will have lower maintenance costs as heating and hot water functions are integral to the boiler and covered by the manufacturer’s warranty
  • Better hot water flow rates (providing your incoming pressure and internal pipework is good)
  • Great if you have multiple bathrooms

Disadvantages

  • Avoid if you have poor water pressure or flow rates
  • Avoid if you have old radiators and pipework
  • More expensive than a boiler swap as it will likely take 2-3 days and will involve a new hot water cylinder.

Upgrading your back boiler

A back boiler is type of regular boiler found in the fireplace. It is no longer possible to replace a back boiler in its existing location.

Your options are:

  1. Retain the existing hot water cylinder and install a regular boiler elsewhere in the property, such as the kitchen or the loft. This is the most cost effective options but leaves all the other system components (cylinder, pumps valves etc) outside the boiler manufacturer’s warranty
  2. Remove the hot water cylinder along with the back boiler and install a combi boiler, providing your water pressure is sufficient. More work and therefore more expensive but it gives a more comprehensive manufacturer boiler warranty (both the hot water and heating is covered) and frees up space.
  3. Install a system boiler in a new location and replace the hot water cylinder with a steel cylinder. Worth doing if you have multiple bathrooms in frequent use, otherwise go with a combi.

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