Shaun Dunn Your boiler might have run all summer without giving you any bother. Or maybe it’s been making a strange noise you’ve been hoping will sort itself out. Either way, the real test comes when the temperature drops and you need your heating every day.
Heating a bit of water for the morning shower is one thing. Keeping your home warm through a Scottish January is quite another. Light summer use can hide problems that only show themselves once your boiler starts working properly again.
So before the cold really sets in, there are a few checks worth doing. Some are simple jobs you can safely handle yourself. Others need a Gas Safe engineer. Here’s how to tell the difference.
Key Takeaways
- Book your annual boiler service in September or October, before winter breakdowns start filling the diary. In October, a slot is usually a week or two away. By December, a non-urgent job can mean waiting three or four weeks.
- Check your boiler pressure with the heating off. Most systems should sit around 1 to 1.5 bar when cold, although the right pressure varies between models, so check your manual. If it drops too low, your boiler can lock out.
- The Energy Saving Trust recommends heating your home to around 18 to 21°C in winter. There’s no saving in leaving the heating running on low all day.
- Never use a naked flame to thaw a frozen pipe. Warm water or a hot water bottle against the frozen section is the safe way to do it.
Why Winter Boiler Preparation Matters
Your boiler gets a fairly easy time of it during summer. A short burst of hot water in the morning might not reveal limescale narrowing the heat exchanger or a pump bearing that’s starting to wear. Once the heating’s running for hours every day, those problems are much more likely to make themselves known.
A few warning signs are worth watching for before winter really gets going: banging or gurgling from the boiler or pipework, an error code on the display, a home that’s taking longer to warm up than it used to, or radiators that are warm at the bottom but cold at the top.
Timing helps too. Get your boiler checked in October and you’re less likely to be queueing behind emergency breakdowns come December. Gas Safety Week runs every September, so it’s a handy reminder to get your annual service booked rather than waiting until the heating stops working.
Should You Keep Your Boiler Running Through Winter?
If you’re going away for a couple of weeks, turning the heating off is generally fine as long as you’re not expecting a hard frost and the boiler’s frost protection stays switched on.
Most built-in frost protection systems monitor the temperature of the water inside your boiler. If it falls to around 5°C, the boiler fires up to protect itself. That temperature varies by model though, so check your manual rather than assuming yours works the same way.
One thing worth flagging: your boiler’s frost protection protects the boiler itself. It doesn’t necessarily protect pipes running through a cold loft or garage. Those still need proper lagging or a separate pipe thermostat.
If you’re leaving the house empty during freezing weather, it’s worth asking a neighbour or family member to pop in every few days. Check your home insurance policy too. Many policies require you to keep the property at a minimum temperature, commonly around 12 to 15°C, or drain the system if you’re away beyond a certain period.
For everyday heating, switching your heating on and off when you need it is cheaper for most homes than leaving it ticking away on low all day. Your house is constantly losing heat, so the longer you keep it warm, the longer that heat loss continues.
A hard freeze is different. Keeping your home at around 12 to 15°C overnight can be safer than switching the heating off completely. And if you’re trying to stop the house cooling down too quickly, loft insulation at the recommended 270mm depth will make more difference than fiddling endlessly with your boiler settings.
Getting Your Boiler Winter Ready: The Essential Checklist
Most of the jobs you need to get your boiler winter ready are straightforward enough to tackle yourself. Give yourself an hour on a Saturday and you can get through most of them. There’s just one part you’ll need to leave to a Gas Safe engineer.
- Check the pressure gauge while the heating is off. If it’s low, top it up. We’ll explain how in Bleeding and repressurising your boiler below.
- Bleed any radiators that are cold at the top but warm at the bottom.
- Lag exposed pipework in your loft, garage or beneath sinks.
- Test your carbon monoxide alarm using the test button. Check the end-of-life date printed on the unit too. They typically need replacing after 7 to 10 years, and yours should be marked to BS EN 50291.
The boiler service itself is best left to the professionals. Before anyone works on your boiler, ask to see their Gas Safe card and check the registration number at gassaferegister.co.uk. Under the Gas Safety (Installation and Use) Regulations 1998, only Gas Safe registered engineers can work on gas boilers and appliances.
If you’ve got a combi boiler in reasonable condition, a standard service will usually include checks of the gas pressure and flue gas readings. The flue is simply the pipe that takes exhaust gases safely outside. Your engineer will also inspect the burner and seals, clear the condensate trap and test the safety shutoffs.
Thermostat Settings for Winter
You don’t need every room in your Edinburgh home sitting at exactly the same temperature.
The Energy Saving Trust recommends around 18 to 21°C for the rooms you use during winter. If one room needs to be cooler, use the thermostatic radiator valve rather than turning down the whole house. Those are the numbered dials you’ll usually find on the side of your radiators.
That means you can keep your living room comfortable while running a bedroom or spare room a little cooler. Much better than making everyone cold because one room gets too warm.
Bleeding and Repressurising Your Boiler
If your radiator is warm at the bottom but cold at the top, there’s probably air trapped inside it. Bleeding the radiator lets that air escape so hot water can circulate properly again.
You’ll need a radiator key and a cloth or small container.
First, switch the heating off and let everything cool down. Then work through your radiators one at a time. Turn the radiator key about a quarter turn anticlockwise. You should hear a hiss as the trapped air escapes. As soon as water starts coming out, close the valve again.
Once you’ve finished, check the pressure gauge on your boiler. Bleeding radiators causes the system pressure to drop, so you may need to top it back up.
You can do that using the filling loop underneath the boiler, usually a braided silver hose with a valve at each end. Open it until the pressure returns to the green zone, then close both valves fully.
If you’re constantly having to bleed your radiators, there may be sludge circulating around the system. That’s usually solved with a power flush rather than repeated bleeding. A magnetic filter fitted to the return pipe catches that sludge and helps stop it travelling back through your heating system.
Pressure that keeps dropping after you’ve bled and repressurised the system is another matter. If you’re topping up more than once or twice a year, you could have a leak or a failed expansion vessel rather than normal pressure settling.
On boilers more than about ten years old, an expansion vessel losing its air charge is the most common cause. That’s not one to tackle yourself. Recharging the vessel needs an engineer.
Protecting Pipes From Winter Freezing
It’s usually not the nice warm pipes inside your house that freeze. It’s the forgotten ones in the loft, garage or outhouse, or the run clipped to an outside wall that nobody’s looked at for years.
When water freezes, it expands. That can crack the pipe, and you might not discover the damage until everything thaws and water starts leaking out. Not ideal, especially if it happens while you’re away.
Foam pipe lagging is an easy bit of prevention. You can pick it up from pretty much any plumbing merchant and push it onto the pipe by hand. Make sure it matches the size of your pipe, and don’t leave gaps around bends, joints and valves. Those exposed little sections are exactly where freezing can start.
Pay particular attention to your condensate pipe. That’s the plastic pipe that carries acidic waste water from a condensing boiler to a drain. If part of it runs outside, it’s especially vulnerable when temperatures drop, so make sure it’s properly lagged.
If the condensate pipe does freeze, your boiler will normally stop and show a fault code. Look for the frozen section along the outside run, particularly around bends or near the gully.
To thaw it, pour warm water over the frozen section or hold a hot water bottle against it for a few minutes. Don’t use a blowtorch, heat gun or naked flame. Once the ice has cleared, reset your boiler.
If the same pipe freezes again that winter, there’s probably a bigger issue with the run itself. It may need rerouting inside or replacing with a larger pipe.
Common Winter Boiler Faults in Edinburgh Homes
Winter has a habit of finding problems that weren’t obvious in summer. Most callouts come down to pressure, frozen pipework or an existing fault that only becomes noticeable once the boiler is working hard every day.
Won’t Hold Pressure or Keeps Locking Out
Start by checking your boiler pressure. If it’s low, top it up and try resetting the boiler by holding the reset button for a few seconds.
You can also look at the flue terminal outside. If it’s frosted over, blocked with leaves or covered by a nest, the fan has to work harder and the boiler can trigger an overheat lockout.
If you reset the boiler and it locks out again straight away, don’t keep pressing the button and hoping for a different answer. At that point it’s worth booking a boiler repair to find out what’s actually causing it.
Pilot Light Keeps Going Out
If an older boiler’s pilot light goes out once after a particularly windy night, that’s one thing. If it keeps happening, there’s likely a fault that needs looking at.
It could be a failing thermocouple, which is the safety sensor that shuts off the gas when the flame goes out, or a draught reaching the boiler. Both need a Gas Safe engineer.
And if you can smell gas, don’t try to relight anything. Turn the gas off at the meter, open your windows and call 0800 111 999.
Heating Works but Hot Water Doesn’t, or Runs Hot and Cold
The water coming into a combi boiler can be close to freezing in January. That means it takes longer to heat, and you might notice the flow dropping slightly. That part can be perfectly normal.
If your heating works but the hot water stays cold, the problem is often the diverter valve. That’s the part that directs the boiler’s heat either towards your radiators or your hot water, depending on what you’re asking it to do.
Edinburgh and most of the Lothians have soft water, so limescale tends to cause fewer problems here than it does further south. But if your hot water keeps swinging between hot and cold, a scaled plate heat exchanger is the usual cause.
Get Your Boiler Winter Ready With SD Plumbing & Heating
Keeping on top of boiler maintenance matters most when the weather turns and your heating starts working properly again. A service can help pick up developing issues before they turn into a breakdown, while regular checks can keep your system running the way it should through winter.
If you’d rather leave your winter boiler maintenance to someone who deals with this every day, give us a call. Our Gas Safe engineers can service your boiler, investigate pressure problems, strange noises and heating faults, and explain what we’ve found in plain English before we do anything.
We give you a fixed price before we start, so you know what the job’s going to cost from the outset. And if something does go wrong when you need your heating most, we’re also available for 24/7 emergency callouts.
Get in touch with SD Plumbing & Heating.
