How do I improve hot water pressure from a gas combination boiler?

Question

I have a gas combination boiler (no hot water tank). The hot water pressure isn't very good though - the showers and hot taps come out with maybe half the pressure when compared to the cold straight from the mains.

Given that the mains pressure is good what is the best way to get more of that pressure through to the hot water?

My boiler is a 6 year old Ferroli F24 - would a new boiler make a significant improvement? Given the expense I'd rather only do that if it both the only way and guaranteed to make an improvement.

Answer 1

I'm in the UK, we got a new recently due to the rebate recently offered on really old boilers.

If you get a decent boiler it provides savings because it is more efficient. They are called "condensing" combination boilers - the condensing action reclaims lost heat, I think.

We got a Vaillant, who also make the glow-worms. Never heard of Ferroli. And yes we get decent hot water pressure. I would check with a few plumbers/gas engineers, just get a few quotes, and also check the boiler specification for max flow rate.

Couple of tips if you do get a new boiler be sure to specify exactly where the pipes go (if you change location), get one of the remote controls (very handy, and allows you to put boiler in loft), and also specify exactly how you want the magnaclean device fitted (collects sludge from central heating). Ours is unfortunately very prominent - we need to move it.

Also, we went for a really big powerful boiler, so more than enough water but tbh probably a bit too big for our house: bigger may not necessarily always be better.

I'd only get vaillant, glowworm, or worcester-bosch, btw.

Answer 2

Your boiler has a limit to its heat output, if you find you get more hot water flow when you turn down the temperature of the hot water, you are hitting the heat output limit. In winter this is more of a problem as the cold water is colder.
A bigger boiler would help a bit, or if you have space converting the system to use a main pressure hot water tank, however there are other options worth looking at as well.

A Gas Saver that users the waste heat from the boiler to preheat the cold water may help. You can get them for a few makes of boilers.

Most boilers, even high efficiency SEDBUK "A" rated condensing boilers, still lose a substantial amount of heat through the flue outlet. The GasSaver captures this heat and uses it to help generate hot water for domestic use.

You could also have a small hot water tank that is heated on the radiator circuit to preheat the cold water before it goes into the boiler. This is one example of such a setup, however it should not be to hard to find the bits to make your own if needed.