Every year, the first cold week in Islamabad and Rawalpindi brings the same problem to thousands of homes: you turn on the hot tap, wait, and the water stays cold. Gas geysers sit unused for most of the summer, and when winter arrives, small issues that built up over those months suddenly show up all at once.
The good news is that most geyser problems have a handful of common causes, and some of them you can check yourself in a few minutes. This guide walks through the eight most common reasons a gas geyser stops working in winter, what each one looks like, and when it is time to call a technician.
Safety first: if you smell gas, stop
Before you touch anything, take a moment to smell the area around the geyser. If you notice the smell of gas, do not light a match, do not switch any electrical switch on or off, and do not try to relight the pilot. Close the gas valve, open the doors and windows, get everyone out of that area, and contact your gas company or a qualified technician. A gas leak is not a do-it-yourself job.
Also remember that a gas geyser burns fuel and produces carbon monoxide, a gas you cannot see or smell. A geyser should never be installed inside a closed bathroom or a room without proper ventilation and a working flue pipe to the outside. Carbon monoxide poisoning from badly installed geysers and heaters causes deaths in Pakistan every winter, and it is entirely preventable.
1. Low gas pressure
This is the most common winter problem in Pakistan and often has nothing to do with the geyser itself. When everyone in the area turns on heaters and geysers at the same time, especially in the early morning and evening, gas pressure drops. The geyser flame becomes weak or keeps going out, and the water only gets lukewarm.
How to check: Look at your stove flame at the same time. If the stove flame is also small and weak, the problem is supply pressure, not your geyser. Try running the geyser at off-peak hours, such as late morning, or keep a storage geyser on a lower thermostat setting so it maintains heat instead of reheating a cold tank from scratch. Avoid gas compressors: they are banned, they take gas away from your neighbours, and they can be dangerous.
2. The pilot light will not stay lit
The pilot is the small flame that stays on and lights the main burner. If it lights while you hold the knob but goes out as soon as you let go, the most likely cause is a faulty thermocouple (see point 3). If it will not light at all, the pilot tube may be blocked with dust or rust after months of not being used.
What to do: Hold the knob down for 30 to 60 seconds after lighting so the thermocouple has time to heat up. If it still goes out, a technician can clean the pilot assembly or replace the part. This is usually a quick and inexpensive repair.
3. A faulty thermocouple
The thermocouple is a small safety sensor that sits in the pilot flame. When it senses heat, it keeps the gas valve open. When it does not, it shuts the gas off so unburned gas does not leak into your home. Over time it wears out or gets bent out of the flame, and then the geyser keeps shutting itself off even though nothing else is wrong.
Replacing a thermocouple is a common job for a technician. Do not try to bypass or remove it: it is the part that protects your family from a gas leak.
4. A dirty or clogged burner
Dust, insects and rust collect in the burner during the months the geyser sits idle. A clogged burner gives a yellow, uneven or lazy flame instead of a steady blue one, heats water slowly, and can leave black soot marks around the burner area. A yellow flame also means incomplete burning, which produces more carbon monoxide, so treat it seriously.
A proper service before winter, where the burner and jets are cleaned, usually fixes this completely.
5. Thermostat set too low or not working
It sounds obvious, but check the thermostat knob first. Someone may have turned it down in summer, or it may have been knocked to the lowest setting. If the knob is set correctly and the burner still never switches on, or the water becomes dangerously hot, the thermostat itself may be faulty and should be checked by a technician.
6. Sediment buildup inside the tank
Water in many parts of Islamabad and Rawalpindi carries minerals and sand, and over time these settle at the bottom of a storage geyser. The sediment layer sits between the flame and the water, so the geyser burns more gas and still delivers less hot water. A rumbling or popping sound when the burner is on is a classic sign.
What to do: Flushing the tank through its drain valve once a year removes most of the sediment. If the tank has not been flushed for many years, have a technician do it, because old drain valves can be stiff or leak.
7. No water flow or low water pressure
A geyser can only heat the water it receives. If the cold water inlet valve is partly closed, the overhead tank is empty, or a pipe is blocked, you will get little or no hot water. Instant (tankless) geysers in particular will not ignite at all if the water flow is too low.
How to check: Open a cold tap nearby. If the cold water pressure is also weak, the issue is your water supply or plumbing, not the geyser. Make sure the inlet valve on the geyser is fully open.
8. A blocked flue or chimney pipe
The flue pipe carries the exhaust gases out of the house. Over the summer, birds sometimes build nests in it, or it can get blocked by debris or come loose. A blocked flue is one of the most dangerous geyser faults because the exhaust, including carbon monoxide, has nowhere to go but back into your home.
Signs include soot around the top of the geyser, a smell of burning, or the flame flickering and going out. If you suspect a blocked flue, switch the geyser off and do not use it until the flue has been checked and cleared.
A quick pre-winter checklist
The best way to avoid a cold shower in December is to get the geyser ready in October or early November, before the rush. A good pre-winter check covers the flue pipe, the burner and pilot, the thermocouple, the gas connections for leaks, the thermostat, and a tank flush. It takes far less time than an emergency repair on the coldest morning of the year, and technicians are much easier to book before the season starts.
When to call a professional
Checking the thermostat, the water supply and the gas pressure is safe to do yourself. Anything involving the gas valve, the thermocouple, the burner, a suspected leak or the flue should be handled by a trained technician. Geysers combine gas, fire and pressurised hot water, and a small mistake can be expensive or dangerous.
If your geyser is giving you trouble this winter, Apni Chhat Home Services can send a technician for geyser repair and servicing anywhere in Islamabad and Rawalpindi.
Hard water makes this worse in some areas
If you are in Satellite Town or the older parts of Rawalpindi, scale is doing more damage to your geyser than age is. The mineral deposit coats the heating element, so the water takes longer to heat and the unit burns more gas doing it. People replace the geyser when a descale and service would have fixed it. In newer areas such as Bahria Town and F-17, the more common fault is the connection and the first-time installation rather than the unit. We cover both, across Islamabad and Rawalpindi.