Combi vs Conventional Boiler???

Canucklehead

Good afternoon: I should add...boilers (and the rest of the central heating/DHW system) are only as good as the standard of the installation and annual servicing, regardless of type. Keep in mind, a combi contains all of the required components in one package i.e. pump, divertor valve, DHW production and expansion vessel. How many MSErs have posted about problems with conventional systems eg. failed/leaking cylinders, cold water storage cisterns, feed and expansion tanks, pumps, valves etc....this fact is seldom mentioned in comparisons. For the record (again;)) we have a condensing combi in our 1 bathroom property with excellent mains flow and pressure but if we had more than one bathroom, we would fit a system boiler with an unvented cylinder.

Condensing boilers (all types) will not experience the same life span (despite the best efforts of your favourite RGI) as, for example, a Netaheat or a Bermuda.

HTH

Canucklehead

thechippy

Canucklehead wrote: »

Good afternoon: I should add...boilers (and the rest of the central heating/DHW system) are only as good as the standard of the installation and annual servicing, regardless of type. Keep in mind, a combi contains all of the required components in one package i.e. pump, divertor valve, DHW production and expansion vessel. How many MSErs have posted about problems with conventional systems eg. failed/leaking cylinders, cold water storage cisterns, feed and expansion tanks, pumps, valves etc....this fact is seldom mentioned in comparisons. For the record (again;)) we have a condensing combi in our 1 bathroom property with excellent mains flow and pressure but if we had more than one bathroom, we would fit a system boiler with an unvented cylinder.

Condensing boilers (all types) will not experience the same life span (despite the best efforts of your favourite RGI) as, for example, a Netaheat or a Bermuda.

HTH

Canucklehead

Ha, You beat me to it, I was just about to say the same.
Regarding reliability you have to look at the whole picture. System boilers are pretty much the same as a combi, it's just that they don't contain the pump, diverter valve or a secondary heat exchanger. They still have the nuisance pcb's, sensors etc.

Because a combi contains everything, if the pump goes, the boiler gets the blame. If the pump goes on a conventional system, the pump gets the blame.

A lot of the unreliability issues also stem from when combi's were quite new on the market. The latest ones are a vast improvement.

Also, as above, unreliability is provoked through a poor installation and not cleaning the system out properly, which is all too common.

bockster

Cardew wrote: »

The average gas consumption in UK is 20,500kWh.

So heating a 4 bed detached house with 4 occupants with an annual consumption of 6,600kWh - at a cost of approx £200pa is remarkable - especially as it is not a new house. So you are atypical.

Again your post gives the impression that it is the change from conventional to combi boiler that has saved you most of the 10,000kWh and of course it is the efficiency of any new boiler that will be the major reason for any savings for most people. However as said above your consumption is atypical.

Incidentally, some combi's do have a pilot light and others have their own internal HW tank. Although I haven't investigated the subject, I can see no reason why a new conventional boiler need have a pilot light.

Obviously there are advantages having combi, and vice versa, however like so many things on MSE the financial savings are often hugely exagerated.

Also despite what the well respected plumbers, who have contributed above, state, there are strong views amongst plumbers about combi reliability.

'Mike the Boilerman' who seems to have a good reputation for his website states:



http://www.miketheboilerman.com/boilertypes.htm

hi cardew,
yes my situation may be atypical, i was just wishing to demonstrate what can be achieved with both a change of boiler and change in the way you use it.

hmmm, thinking, if uk average gas consumption is about 20000kwh's, maybe all the combi owners are using 6600kwh's and all those with conventional boilers are using 33400kwh's!!!!!!