Gas Boiler Not Performing

JimmyO

Hi All,

Moved into an apartment and the Gas Boiler isn't performing as I think it should. After being on for 2hours there's not enough water for 2 showers.

In a previous apartment this was more than enough.

Has anyone any tips for improving performance?

As far as I know its a 30"x18" cylinder and it's well insulated.

It has an immersion fitted also but want to avoid this as Gas is cheaper.

10-10-20

That sounds like a small cylinder.
Is there a power-shower attached?
Can you feel the level of the hot water on the cylinder prior to the shower? Does it feel hot to the bottom? At what level is the hot water after the first shower?

You many need to give the cylinder more time to recover after the first shower.
Also, check that the gas heater is set for ~65 degrees C (pipes will be just too hot to touch) and maybe set it running before the first shower commences.

ART6

10-10-20 wrote: »

That sounds like a small cylinder.
Is there a power-shower attached?
Can you feel the level of the hot water on the cylinder prior to the shower? Does it feel hot to the bottom? At what level is the hot water after the first shower?

You many need to give the cylinder more time to recover after the first shower.
Also, check that the gas heater is set for ~65 degrees C (pipes will be just too hot to touch) and maybe set it running before the first shower commences.

That is a small cylinder. Bearing in mind that the cold water feed to it is in the bottom and the hot output at the top, when you run the first shower you are adding cold water and potentially diluting the hot. 10-10-10 is right. You will need to leave the second shower for longer to let the system recover with a tank that size.

Pete67

That cylinder holds about 125 litres of hot water. A shower typically uses about 10 litres a minute, but not all of it comes from the hot water cylinder, as it is mixed with cold water to control the temperature. Say the hot/cold split is 60/40, then there is enough hot water for the shower to run for about 20 minutes before going cold, assuming the cylinder was full of hot water to start with, and there are no other users.

If the boiler is running when the shower is in use this time will be extended slightly, but unless you have a fast recovery cylinder with controls designed to channel the full boiler output into heating hot water it will not be able to keep up with consumption.

If you have a power shower, then you could be using 15 to 20 litres a minute, and the hot water will run out much more quickly.

If is is the case that the boiler is not heating the cylinder fully in 2 hours, and the radiators are heating normally, then there may not be enough flow to the heating coil in the cylinder. This can be easily increased, usually by opening a balancing valve slightly more than is is already. This valve will be located on one of the two pipes entering the side of the hot water cylinder. Don't open it too far or you may reduce the hot water supply to the radiators. 1/2 to 1 turn open from fully closed is usually about right.

JimmyO

Hey All,

Thanks for the replies.

Really sorry! I got the cylinder size completely wrong.

I had been googling for solutions and lots of sites had that size listed as being a standard cylinder on a lot of sites so I presumed that's what I had.

To be honest I don't know the exact dimensions but if I'd used my brain at all i'd have realised the size I listed was wrong!!! To look at it it's about 5' tall and I'd say maybe 30" in diameter. It the same size as the tank I've seen in any recent build apartment.

There's no power shower attached.

Pete67 - The rads are heating fine. I'll try the balancing valve later. From memory there are two paralell pipes near the bottom and one has a red wheel type tap on it. It that what I'm looking for? Would a 1/4 or 1/2 turn do it?

Pete67

JimmyO wrote: »

Pete67 - The rads are heating fine. I'll try the balancing valve later. From memory there are two parallel pipes near the bottom and one has a red wheel type tap on it. It that what I'm looking for? Would a 1/4 or 1/2 turn do it?

Depends. The cold water supply to the cylinder enters near the bottom and may have an isolating valve close to the cylinder. This one however should be fully open.

The cylinder is heated by a coil inside it which get a supply of hot water from the boiler. The flow and return connections to the coil are usually one above the other, and one of them should have a balancing valve fairly close to the cylinder itself. If you're not sure which one it is post up a couple of pictures and we'll identify it. It would usually be a 3/4" valve with a red handwheel. Open it another 1/2 turn and see how you get on. The worst that can happen is that you get too much flow to the coil and not enough to the radiators, as water takes the path of least resistance. The purpose of the balancing valve is to introduce a controlled amount of resistance to the coil circuit to prevent this happening.

JimmyO

Thanks so much Pete!

The apartment is a really good build and takes very little to heat it.

I'll gladly sacifice a bit of heat in the rads if it means I can have a decent shower!!

I'll try and get some pics but the pipes are one above the other so I reckon you've pointed me in the right direction.

One question though, can I cause damage if I turn the handwheel too far?

Reyman

Get your landlord to put in an immersion heater. Easiest cheap solution.

JimmyO

Reyman wrote: »

Get your landlord to put in an immersion heater. Easiest cheap solution.

Hi Reyman,

There is an immersion fitted but as Gas is so much cheaper I want to avoid using it

partyguinness

Gas Boiler Not Performing

Have you tired talking to him? Foreplay?:p

Reyman

JimmyO wrote: »

Hi Reyman,

There is an immersion fitted but as Gas is so much cheaper I want to avoid using it

I wouldn't be too sure about that. Heating water for half an hour with a 2kw immersion only costs 25cents or so. I'm doubtful if gas is better than that given the inefficienceis of the boiler and the piped indirect system of heating water.
Either way it's only a few pence a day so go for it man!

Pete67

JimmyO wrote: »

One question though, can I cause damage if I turn the handwheel too far?

No, as long as you don't force the valve beyond the fully open point. It should turn freely. Just open it another 1/2 turn or so.

You will know if it is not open enough if you wait until there is no hot water left in the cylinder, switch on the heating and then feel the temperature at the inlet and outlet of the coil. The inlet will be quite hot, so be careful, but you are more interested in the outlet. Once the inlet is hot, say 5 mins after switching on the boiler, the outlet should be about 10 degrees lower that the inlet, so still pretty warm. If it is cold or only slightly warm, then there is not enough flow to the coil and you need to open the balancing valve a bit further. Hope this makes sense.