System or combi boiler?

[newgal85]

Hi guys

We want to do a whole revision of our boiler system- we currently have a system boiler at the moment with a water tank upstairs. One bathroom currently with electric shower and a 2nd bathroom still being constructed. What do you guys advise? Please let me know if this is in the wrong forum and I can move accordingly - thanks

 

[JohnnyM]

I went on a Baxi product training day last week (Baxi 600 series) and not one of the of the installers there had a Combi in their own house. A bit of food for thought?

 

[JohnnyM]

Looks like I went on it twice

 

[fixitflav]

I went on a Baxi product training day last week (Baxi 600 series) and not one of the of the installers there had a Combi in their own house. A bit of food for thought?

Friend of mine runs a gas company, made redundant by BG early 90s, struggled for a couple of years, then combis took off and he's never looked back, gets most of his work from combi callouts. He wouldn't have a combi in his own place.

 

[kasser]

Doesn't a system or heat-only boiler use less gas than the equivalent combi one?

With the combi, water needs to be heated instantaneously, you need a big power output for that. With system boilers, you heat up a tank of water then keep it warm.
So cheaper to run a system boiler.

 

[Scott_D]

Doesn't a system or heat-only boiler use less gas than the equivalent combi one?

With the combi, water needs to be heated instantaneously, you need a big power output for that. With system boilers, you heat up a tank of water then keep it warm.
So cheaper to run a system boiler.

Would be good to know the actual figures for this

 

[kasser]

You

Would be good to know the actual figures for this

You don't replace a 24kW combi with a 24kW system?
If you look at the heat input of system boilers, the range is much lower than combis.

 

[Scott_D]

You

You don't replace a 24kW combi with a 24kW system?
If you look at the heat input of system boilers, the range is much lower than combis.

I mean the gas useage of a combi vs a boiler and cylinder

 

[fixitflav]

I mean the gas useage of a combi vs a boiler and cylinder

For a given property, combis usually rated 2-3 times higher output than system or heat-only, due to the need to get a decent hot water flow. So instantaneous gas usage is higher (can mean increasing gas pipe size). Overall consumption for CH probably doesn't vary much, just depends on the efficiency of each. For HW, depends on type of use. If it's all in one lot each day, combi could be better. If (more likely) it's many small draw-offs combi likely to be worse.

 

[newgal85]

Thank you to everyone for your advice - I've gained a lot if knowledge from this forum!

Decided to go with system