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Discuss System or combi boiler? in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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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
 
How many bedrooms / size of house eg standard 2 up 2 down ?
 
Combi Boiler if your keeping the elec shower
 
If the 2nd bathroom is only a guest bathroom then I agree combi and keep electric shower if you have 2 bathrooms used full time then maybe look at keeping tanked hot water.
 
Do you have a vented or unvented hot water cylinder
 
And when you say Electric shower do you mean a shower that heats cold water within itself or do you mean it is a power shower that pumps out hot and cold water. I ask only as I’ve never heard anybody saying about an electric shower being better than one from a combi boiler or unvented
 
A combi boiler will never perform as well as an unvented cylinder. If you have the space for a cylinder, or already have one I would always recommend that a cylinder is used. Combi boilers are often mis-sold by installers as an "easy option". Combi boilers are great in smaller properties with only one bathroom but anything above that, it's unvented cylinder all the way for me. If space is a major concern, a combi can be a good option. You already have a cylinder (not sure if vented or unvented?) so I would use that space and keep/install an unvented cylinder for performance reasons and also for future proofing if another bathroom were to be added or you wanted to move away from electric showers for some reason.
 
Combis came from the continent in the 80s they were installed in small houses and flats where an F&E tank was impossibke,and space for a cylinder and cold water storage
tank limited. What happened was installers jumped on combis cause they were an easy
one box installation. Then big combis appeared with bigger flow rates. Problem the big combis can heat more hot water than the mains can provide.
System set up answers all these problems well esp with pressurised cylinder..ie unvented. Centralheatking
You can go get a mains booster and steal your neighbours water until I turn up and put my own booster in then your back to a virtual desert.
 
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
Neither - go for a heat-only boiler. :)
 
And when you say Electric shower do you mean a shower that heats cold water within itself or do you mean it is a power shower that pumps out hot and cold water. I ask only as I’ve never heard anybody saying about an electric shower being better than one from a combi boiler or unvented
And as asked before
 
Do you have a vented or unvented hot water cylinder
And when you say Electric shower do you mean a shower that heats cold water within itself or do you mean it is a power shower that pumps out hot and cold water. I ask only as I’ve never heard anybody saying about an electric shower being better than one from a combi boiler or unvented
Hi Riley - its a vented cylinder and ekectruc shower that heats water up within the heating element inside.
 
A combi boiler will never perform as well as an unvented cylinder. If you have the space for a cylinder, or already have one I would always recommend that a cylinder is used. Combi boilers are often mis-sold by installers as an "easy option". Combi boilers are great in smaller properties with only one bathroom but anything above that, it's unvented cylinder all the way for me. If space is a major concern, a combi can be a good option. You already have a cylinder (not sure if vented or unvented?) so I would use that space and keep/install an unvented cylinder for performance reasons and also for future proofing if another bathroom were to be added or you wanted to move away from electric showers for some reason.

Hi Stigster - Thanks! I forgot to mention water pressure is low downstairs and decent upstairs and water is coming through led pipes (we just discovered whilst digging as its a very old house)

Is it worth getting megaflo ?
 
Amazed that you think you’ll get a better shower from electric. Even an 11kw is usually rubbish comparatively
 
Amazed that you think you’ll get a better shower from electric. Even an 11kw is usually rubbish comparatively
I guess I have always had electric shower so I don't know how the standard shower pressure will be - if it should be better than I'm happy to change
 
It should definitely be better. Assuming your mains pressure is adequate. If it’s not then that’s a whole different ball game
 
Oh I didn't know there was this option?

As you have a system boiler at present I assume the water tank upstairs is the cold water storage tank, in the loft. System boiler has a built-in expansion vessel, so no F/E tank (in loft).
Others might disagree, and it depends on the details of your existing set-up, but heat-only would be my preference. Then the various parts - boiler, pump, diverter valve are separate. It's a lot easier to see what's going on, and if any of them goes wrong there's a good chance you can diagnose and fix the problem yourself. With a system or combi boiler you'd probably need a GSR guy out. You still have the option of installing a F/E tank, or an expansion vessel separate from the boiler.
 
As you have a system boiler at present I assume the water tank upstairs is the cold water storage tank, in the loft. System boiler has a built-in expansion vessel, so no F/E tank (in loft).
Others might disagree, and it depends on the details of your existing set-up, but heat-only would be my preference. Then the various parts - boiler, pump, diverter valve are separate. It's a lot easier to see what's going on, and if any of them goes wrong there's a good chance you can diagnose and fix the problem yourself. With a system or combi boiler you'd probably need a GSR guy out. You still have the option of installing a F/E tank, or an expansion vessel separate from the boiler.
Yep you are right- I have a cold water tank in the loft and hot water tank next to upstairs bathroom (which is very old so definitely needs cleaning out)
 
Hi Stigster - Thanks! I forgot to mention water pressure is low downstairs and decent upstairs and water is coming through led pipes
That does not make a great deal of sense. What do you have downstairs, and are you refferring to hot or cold, or both. Whatever scenario I can think of will result in a greter pressure down than up - if iot is noticeable at all.
For it to be opposite suggests that there is/are valve(s) in play
 
Not sure I’d have another combi, in my last house (2 up 2 down) we had a Worcester 28si 2, which was great, but I work on a lot and majority of them aren’t that great. Just my opinion though.
 
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
If you want a powerful shower, the key is to make sure that the combi boiler is powerful enough to supply a hot water flow rate of at least 12-15 litres a minute.
 
Yep you are right- I have a cold water tank in the loft and hot water tank next to upstairs bathroom (which is very old so definitely needs cleaning out)
Consensus seems to be that unvented cylinder is the way to go for improved shower, provided your mains water pressure and flow are adequate. Needs checking before finally deciding. Specially if your current cylinder is on its last legs.
Is there anything wrong with the existing boiler? If you decide to replace it, you could go for heat-only, if there's room to install separate and expansion vessel, if not another system boiler.
 
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?
 
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.
 
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.
 
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
 

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