Combi or conventional?

[luco_bellic]

Hi guys,


I have moved in to a new property and our old conventional boiler has failed completely. It is a large 3 bed flat on the second floor, about ~40m from the gas meter reading (on the ground floor) and water pressure in the kitchen is about 12 litres per minute.


The first engineer, after checking everything on site has given me a quote for ~£3000 specifying Vaillant Ecotec 831 Plus. I have decided to go for a second opinion and asked other 3 companies (including BG) to provide me quotes for the same boiler - after investigation on site they all got back to me saying that combi boiler is a NO, as I am living too far away from the gas supply and the gas pipe is only 15mm. One engineer considered system boiler, but after measuring water pressure in the kitchen said that it is not enough (must be 18 litres per minute), therefore system boiler is also out of the question. All 3 companies suggested that I can only upgrade the existing system by installing new conventional boiler (like Worcester 15ri) and the water tank.


When I got back to the first engineer with all those findings, he said that I have got 22mm pipe which is enough for the combi boiler.


So just to recap: I have got Vaillant certified installer (recommended to me by few colleagues) specifying Vaillant Ecotec 831 Plus on one hand, and three other companies (including British Gas) saying that the only way forward is to upgrade existing system (cheapest quote was just more than £4000). Needless to say that besides BG, other 2 companies are also Vaillant certified installers.


I would really appreciate if someone could clarify: if I go for a combi boiler, how important is that gas meter is ~40 metres away? Am I right to assume that if 22m pipe coming into my cupboard it is going to be sufficient?


What would be your suggestion: try the luck with the combi boiler or upgrade the existing one? Would there be any significant difference in regards of performance?


Also if I go for a combi boiler, is there any way to get some sort of insurance from the installer? For example, if I contact the Vaillant directly after installation to check the performance and it turns out that boiler is underperforming as was not installed according to the manufacturer's specifications, would it be possible to get the money back?


Thanks a lot in advance.


Regards,
Luco

 

[newcastle phill]

Insurance if it isnt installed correctly -
Most people call it small claims court.

if you are doubting what you have been told by an engineer then simply get more quotes from others and raise those specific issues.
The job hasnt even been started and your looking for ways to get your money back if it doesn't meet your expectation.
If the engineers competent then the MI is a given.
Perhaps that isnt the wisest thing to ask on a plumbing forum

 

[stevetheplumber]

even 40metrers of 22 isnt going to be enough for a 30kw boiler and if its 15mm its not enough for the 15kw

 

[PhoenixServices]

Also can't understand why the system boiler has been ruled out due to flow rate. A system boiler doesn't need a mains flow rate just 1 bar of pressure to fill the system. Unless you are getting this mixed up with an unvented cylinder.

 

[stevetheplumber]

where are you luco maybe you could get another quote from someone here all your quotes seem a little high

 

[solutions]

Luco I think you may be confusing 2 important factors. Gas regulations and many appliances require that a minimum gas pressure be available to the appliance at its location. The longer the pipework from the meter to the appliance the more pressure is lost. To reduce the amount of pressure lost larger diameter pipe is used. If your gas pipe is 15mm then it will not provide sufficient pressure for many gas appliances (although I highly doubt it is 15mm for the whole 40M back to the gas meter) if possible the gas pipework could be upgraded to a size that will supply the new appliance with an appropriate pressure. A combi boiler heats hot water as you need it using the water supplied by your incoming main. Much like the gas, if the pipework supplying your cold water to the combi can not provide a high enough flow rate of water at the right pressure it wont work effectively if at all. Without seeing your flat and its pipework it is impossible to say whether either the gas pipework or cold main pipework or both can be upgraded to permit a vaillant 831 to be fitted. As has been suggested get some more quotes particularly from reputable local independent Gas Safe registered engineers and make a point of raising your concerns regarding the comments made and advice given by the other companies that have quoted.

 

[oz-plumber]

Did my post get deleted???

If it did -most definately deserved it.

 

[newcastle phill]

Havent seen it yet was just looking before

 

[luco_bellic]

Thank you for all the answers, your help is very much appreciated.


My main concern is whether I should "risk" with the combi boiler Vaillant Ecotec 831 Plus or upgrade to conventional Worcester 15ri and replace the cylinder as I have the rest of the infrastructure already (water tanks, etc.)? Would there be a significant difference in performance?

Regards,
Luco