Gas boiler - how does it work exactly?

[Samsean]

Hi,

We are currently looking at renting a property that says it has a gas boiler. How does that work exactly?

The reason I ask is because we had a horrendous experience with another old property we rented, that a had an old boiler that you had to put on two hours before if you wanted to shower, and if the boiler went on then the heating went on too!

Our current place has a combi-boiler and it works perfectly.

So how does a gas boiler work? Thanks!

some gas boilers are combis and some are not.

all modern boilers are "condensing" so much more efficient than older boilers.

It is (almost) impossible to buy a gas boiler that uses a chimney, they all have balanced flues now.

A boiler which is not a combi will have (some kind of) a hot water store or cylinder. Modern boilers will heat modern cylinders in 20 minutes. Old ones may take much longer. It is possible to improve them.

It is usual to control HW and CH separately with timers and thermostats. A few old or bad installations might not do that.

Some old systems always have the HW on if the CH is on.

Only faulty or badly-designed systems always have the CH on if the HW is on. It is possible to fix them.

a gas boiler that is a combi will produce instant hot water, but sometimes at a slower rate.
a non-combi heats up a tank of water which should stay hot until used up.

boilers should have valves and switches that allow you to choose heating, hot water or both.

first - check the property has a current gas safety certificate, and ask to see it before you sign the lease. If refused, walk - this certificate is a legal requirement.

second - find out if the boiler is a combi or not. If it isn't, check the tank - it should be covered in solid insulation. If it is a loose jacket it is an older tank, possibly older system, probably less efficient.

A combi boiler is a gas boiler.
there are lots of different types of gas boilers - usually divided into 3 typical set ups in domestic homes.

Make enquiries with the letting agent. In particular ask what type of boiler and how old it is.
Note - from a super - modern system you should get hot water in 20 minutes.

snap!

Well, a combi boiler is a type of gas boiler, so it might be like your current set-up. Even if you have a system boiler, where you heat a tank of water, there should be no need to put on central heating to heat water... If you do, sounds like a shonky boiler, so ask your landlord to fix it! But yeah, with a hot water tank, you do have to plan ahead a bit, and set the timer to come on in time for when you like to have a shower. A well insulated tank should retain heat for a while, and it certainly shouldn't qualify as horrendous, but it does require a bit of organisation.

Thanks everyone! I will ask them whether it is a combi boiler or not.

if it has a cylinder, tell us what colour it is (this is not a joke)