How to solve the issue of frozen pipes this winter

Heating expert Neil Jenkinson, Performance Manager at Wheldons in Newport Pagnell, offers some timely advice from the Heating and Hotwater Industry Council (HHIC) on how to get your heating back on if your boiler shuts down due to frozen condensate pipes. Don’t worry, it’s actually quite a simple problem to solve…

As the temperature needle starts to nudge towards freezing, I thought I would expand on one of my top tips from last month to help you ensure your home stays warm and comfortable in the run up to Christmas.

One of the main problems we see during the colder winter months is boilers shutting down due to external frozen condensate pipes. This also happens to be one of the easiest problems to solve and sometimes even without the need to call an engineer out.

A significant amount of work has been carried out by the Heating & Hotwater Industry Council (HHIC) and its Members with the intention of promoting high quality installations to reduce occurrences of freezing condensate pipes but also to offer common sense advice to individuals to remedy the situation should it arise.


Shutdown due to freezing and blockage of the condensate discharge pipe will usually be indicated by a “fault code” on the boiler’s digital display, or by some other alarm signal (check the boiler operating manual for advice on this).

It is important to confirm that freezing is the cause of the problem before taking any of the remedial action suggested below. Ideally, remedial action should be carried out by a competent installer or service engineer – who will also be able to advise you on ways to help eliminate recurrence in future. Where it is not convenient to await such action, there are a number of methods which householders may wish to try in order to thaw the pipe and free the blockage.


It is likely that the pipe is frozen at the most exposed point external to the building or where there is some obstruction to flow.

This could be the open end of the pipe, at a bend or elbow, or where is a dip in the pipe in which condensate can collect. The location of the blockage should be identified as closely as possible before taking further action.


The pipe can be thawed by applying a hot water bottle, a microwaveable heating pack (the sort used for muscular aches and pains) or cloths soaked in warm water to the exterior of the pipe, close to the point of blockage. Warm water can also be poured onto the pipe from a watering can or similar container.

Do not use boiling water. Note: You should not attempt to thaw a condensate drain pipe which cannot easily be reached from ground level. Be aware that any water used can quickly freeze if it falls on pathways, causing a possible slip hazard.


Once the blockage has cleared, consult the boiler operating instructions or check the manufacturer’s website for guidance on any action needed to clear the fault code/alarm and re-start the boiler.

If this does not succeed you should call in a competent engineer to assess the situation and take further action if required.


If the pipe is successfully thawed and the boiler can be re-started then the following temporary remedial actions may help prevent re-freezing if the severe weather continues…

(a) If the external pipe is not lagged as recommended (see below) then you should try to insulate the pipe with suitable water-proof and weatherproof lagging, in order to prevent re-freezing.

(b) During the cold spell it may help to run the heating system with the boiler thermostat (NB not the room thermostat) set to a high position. Turn back to the normal setting once the cold spell is over.

(c) It may also help to temporarily set the central heating timer/room thermostat controls to “continuous” (24hr) mode, setting the room thermostat overnight to around 15 C.

Again, return to normal settings once the cold spell is over.


British Standards, Building Regulations and boiler manufacturers’ installation instructions allow condensate discharge pipes to run either internally or externally (or a combination of these).

All the above documents give recommendations on how to run the pipe and how/ when use insulation in order to reduce the possibility of freezing. However this may not have been sufficient to prevent freezing in extreme conditions of the type recently experienced.

Should you wish to take action in order to prevent recurrence of pipe freezing by relocating the condensate drainage pipe then more detailed guidance is available from your installer or service engineer.

The Heating and Hotwater Industry Council, HHIC, is a not for profit trade association committed to effectively driving, supporting and promoting the sustained growth of the UK domestic heating and hot water industry. For more information about the HHIC, including its guide for consumers, visit

Winter boiler service for only £80! This price includes a FREE Carbon Monoxide (CO) Alarm Call Wheldons on freephone 0800 2946262, quoting ‘CelebrateMK01’ CO Alarm available while stocks last. Offer valid until December 31, 2018.

This feature was published in the December 2018 issue of Celebrate:MK lifestyle magazine. Read the full magazine above or by clicking on this link.

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