Replacing Gas Boiler with Combi - Copper cylinder implications

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cronley

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Must replace 16 year old system gas boiler that was heating rads & copper cylinder. Thinking of going for new Combi boiler. What are implications for copper cylinder. With Combi, where does water for hot taps come from. Does it come from attic storage tank, through the Combi & from the Combi straight to the taps. If this is the way, is Combi suitable for lime hard water. Heating throgh the coil in the cylinder the old boiler was using a closed water circuit.
One installer said, that for Combi boiler - the system must be changed to a pressurised system - what is this - is he right -gave the impression it was a major job.
Can the copper cylinder & immersion heater be retained with a Combi boiler system - in case there is a gas failure.
 
We have recently (2 months ago) installed a condensing combi boiler and are very happy with it so far. I can't answer all of your questions but will try to help a bit:

"What are implications for copper cylinder." Ours went out in a skip.

"With Combi, where does water for hot taps come from." The boiler heats mains water as it comes in.

"Does it come from attic storage tank, through the Combi & from the Combi straight to the taps." No, you can get rid of your tanks, and you have drinking water coming in at all taps.

I don't know about the rest of your questions, but certainly you need decent water pressure, your county council may give you some information on your area, however they won't guarantee water pressure so you have no comeback if you install a combi boiler and then can't run it due to low pressure.
 
TreeTiger, could you give some more information on the combi condensing boiler i.e. what is "combi condensing", price etc.
 
Thanks tree tiger.
Anybody with info on retaining cylinder & immersion heater with a combi boiler. Plumbing labour - is it cheaper to retain cylinder or take it out - or is there any option - must it be taken out.
Mickeyg - see here for boiler cost - go Gas Boiler - Domestic High Efficiency -http://www.rvr.ie/default.aspx?subj=news/NewsArticleList
 
mickeyg said:
TreeTiger, could you give some more information on the combi condensing boiler i.e. what is "combi condensing", price etc.
Click to expand...
This link will give you a bit of info, plus links to various boiler manufacturers: http://www.heatandplumb.com/acatalog/Gas_Condensing_Combination_Boilers.html

Ours is a Worcester Bosch Greenstar 37cdi, we paid (I think just over) €2000 which was a trade price. I can't tell you what it cost to fit though, because the overall bill was for a whole lot more than just fitting a new boiler, as we extended and refurbished the house which involved a lot of plumbing work.

Here's the Worcester Bosch page on gas combi boilers: http://www.worcester-bosch.ie/specifier/products/gas-boilers/combi
 
I wouldn't fit a combi unless i had a reason, ie freeing up space or maybe cost as for a new build, a combi is easier to fit than a system boiler, it is not that they are bad at what they do, its that they're different to system boiler which heats a cylinder, a system boiler is more simplistic and can be less susceptible to dirty system water, combis have plate heat exchangers that have very small water ways that get easily blocked, effecting hot water performance, if you loss hot water you don't have a hot water back as you do with cylinder and a immersion, unless you are clever enough to fit a electric shower, flow rates can be a problem in a big house, the more taps you open the more the water flow can drop off,
.I would also go for a condensing boiler system or combi, Worcester Bosch and viessmann make good boilers, and i think viessmann give a five year guarantee.
Some installer are fitting combis and cylinders together , they do this by running the kitchen off a combi and the rest of the house of a cylinder, the cylinder needs to fed by a tank as they cannot handle mains pressure unless you fit a unvented cylinder which is a whole other story.
 
Like the other guy said if you want to save space then a combi. To save money I would use a combi. I done an apprenticeship in Germany so im used to these questions. A combi oly heats water when you need it not like conventional burners. Be careful when buying a condensing burner. These do save money buy giving you 109% compared to a combi 93%. But also not many people can explain how they work. You do not need a boiler with a combi but there is no zcirculation pipe. I would personally buy a german brand of burner. Viessmann, Junkers, Vaillant. Look on ebay.de and you will see abig difference in price compared to Ireland.As to pressure. All heating systems are pressurised. Thats why there is an expansion tank. With lime build up that only depends on if your water is heated to more than 60 degrees
 
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