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Plumberpro, Plumber
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Experience:  Heating and plumbing answers. 20 years experience
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About to ditch my 12 year old Keston Duet Celsius 25 with a

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About to ditch my 12 year old Keston Duet Celsius 25 with a 200L Keston Spa. It has never been up to running 22 radiators in a 6 down, 6 upstairs rooms with two showers and 6 wash hand basins. What KW output boiler would I need and will a boiler fit in place of the Keston on the frame and still keep the spa tank. I wondered about a Remeha Quinta Pro 45 or a Vokera Verve. Not looking at cut price boilers fortunately, as lucky to have an NHS pension
Submitted: 1 year ago.
Category: Plumbing
Expert:  Plumberpro replied 1 year ago.
Make sure your gas meter has the output for a high kilowatt boiler. A u6 meter will provide 6m cubed of gas per hour.the rehema 45 uses 5mcubed per hour.For a 22 radiator sytem the main primary pipework should be 28mm, branching off to 22mm and on to 15mm.The kilowatts needed should be worked out to room sizes, building heat losses etc, or work out the is of each rad and total up , plus add 6is for the hot water cyl , plus 2 is for pipework heat losses
Customer: replied 1 year ago.
How do I find if meter is u6 or u5. And how does room sq m relate to boiler KW. What is the is. Vokera Verve mcubed per hour.
Appreciating your advice
Expert:  Plumberpro replied 1 year ago.
Your gas meter will have written on it the type/size. Every room will have a required kw rating needed to heat it sufficiently. If every radiator in your house was a kilowatt you would need a 22kw boiler for example
Customer: replied 1 year ago.
Bit more complicated than I thought. Is there a sq metreage to a KW. What is the "is". So add 2is plus 6is to the is of each room should give me the ideal KW size for a boiler ??
Expert:  Plumberpro replied 1 year ago.
The is was spellchecker changing kw to is, sorry.To be honest a 45 kw boiler would in most cases do the job as long as the pipework is adequately sized.You would most likely need a light commercial pump, ie 25 50
Customer: replied 1 year ago.
Spell check a real bummer sometime. The DHW system has a Grundfos UM 20-07 N 150 pump and CHS has Grundfos UPS 15-50 130 pump. I have a 2 way motorised valve on CH system and a 2 way motorised valve on the HW system. There is an outside weather sensor and all controlled by a Honeywell AQ 6000, like a Brimstone missile, fire and forget. All rads also have TRV's
Expert:  Plumberpro replied 1 year ago.
That's great . But 22 radiators is a big system,just saying and I've been out to loads that have undersized pipework and no matter what you try and do they underperform. Just curious why rehema and vokera though, have a look at the gallant eco tec 46 and veissman.
Customer: replied 1 year ago.
There are large pipes in a circular system with smaller pipes to each rad. I went for these two as they have twin flue pipes. My house is listed and stone/brick wall and they would fit via the flues from the Keston. Would you suggest other makes. I have done a lot of Google boiler makes problems and some boilers seem a nightmare. The Remeha is Dutch, good engineers, but the Vokera is Italian, so not so well made. Ferraris, Lambos ,Alfas and Fiats, all bit unreliable :-)
Expert:  Plumberpro replied 1 year ago.
Yes if you need that flue option , but I would go rehema personally. The Italian boilers aren't great.they last a few years without faults then are better thrown out
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Customer: replied 1 year ago.
Thank you. I will stick to the Quinta Pro 45. Thank you for your help. Will now go and tick the 5 star box.

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