Combi Boiler Questions

[Wurzel83]

Good evening everyone.

Just spent the last 2 weeks researching into Combi Boilers on google and allot of the answers came up here hence I signed up today. I am shortly moving into a 1920s Semi Detached in need of modernisation and would like to replace the Baxi Bermuda Back Boiler with a Combi. I have a few outstanding questions:

1. Can anyone see any problems with me re-routing the CH and HW pipework from the tanks to the location of the new boiler and physically fitting the boiler on the wall and getting a Gas Safe plumber round to connect up the gas and set it to work? Obviously I will remove the old boiler when it has been disconnected.

2. I have decided to go for a Vaillant due to the reviews and threads I have seen. Which magazine also rate them highly. They seem to 2nd best when compared to Worcester Bosch which are expensive. I am however going to get the "Emergency Cover" with AVIVA insurance which covers boiler and CH breakdowns so was wondering - If all repair costs are covered then should I spend the same amount of money on a cheaper brand (Biasi/Ferolli etc) but with more features and power?

3. I do not have cavity walls, I have a single story kitchen extention and will be putting a 4th bedroom in the loft. I have used Boiler Calculators online which point towards the requirement of a 17-20KW however I do not beleive this will be big enough and flowrate is important due to the need for a mixer shower. I was thinking 32KW? Upwards of this the price starts to jump up quite steeply.

4. Can I leave the cold water tank in the eves and use this instead of the mains supply to the boiler? I will also leave the bath and shower cold taps connected to the CWT and as a result not get a reduced HW flow rate when the cold tap is turned on too? Obviously the kitchen CW tap would remain connected to the mains.

5. The current CH system was fitted about 30 years ago. How can I check whether my current radiators, pipes and valves are compatable with a combi? Is it down to diameters and matterials etc?

Thanks in advance.

 

[holty]

1:depends on the commisioning engineer

2:get cheap expect cheap ****.why the service cover when a boilers guaranteed e.g worcester 2-5 years parts and labour good aftercare if installed correctly .vaillant good boilers crap aftersales. have a look at viesmann id better them over the two brands you mentioned .

3:combi boilers are rated on dhw not ch for example a 24kw will give about 9-10 litres per minute a 35kw 14-15 lpm.

4:you need a mains supply to the boiler for the hot water.and the cold feeds would be better off mains.for various reasons.

5:an installer would tell you this solution. and refer you back to points 1-4. about how much incoming pressure and flow you have.location of gas pipe and boiler.

 

[Elkato531]

I usually advise people to have a go at most things but its worth bearing in mind that you will require the updated heating system to operate safely, efficiently and effectively to supply your household with heat and hot water for many years to come. When you think of it in those terms, the cost of paying a professional to do it for you is money well spent.