Do new Combi Boilers waste water

frosty_phil

Hi have an old combi with a pilot light. It takes quite a while before the hot water reaches the taps, all the while water is running to waste. The new boilers do not have pilot lights so a fan has to purge the boiler, meaning it will take even longer to get going. Is this going to be a real nuisance? and will it be a considerable waste of water.

Mankysteve

Your pilot light will not add a significant amount of heat to your water so having a constant pilot light compared to a modern one won't make any real difference.

You can get combi boiler that have a instant heat function but waste some gas in the process. The heating with combi is yes they waste but in theory will save more gas then a hot water tank. Modern hot water tanks are pretty good now though but of course if you don't have the space then you cant have one.

Garsh

Hi, I'm new to this so please bear with me - I have a Worcester combi boiler that was completely rebuilt 1 year ago under the manufacturers service contact...and I mean completely. Ot was off the wall and new backplate and all components replaced. However, recently the shower runs hot for about 30 secs then cold for 30 secs and just keeps on doing this - has anyone any ideas as the service engineer can't fix it.

Thanks

Cardew

Mankysteve wrote: »

Your pilot light will not add a significant amount of heat to your water so having a constant pilot light compared to a modern one won't make any real difference.

You can get combi boiler that have a instant heat function but waste some gas in the process. The heating with combi is yes they waste but in theory will save more gas then a hot water tank. Modern hot water tanks are pretty good now though but of course if you don't have the space then you cant have one.

Firstly the pilot light consumption can be significant.

Secondly the Combi boilers the provide 'instant' hot ware achieve this by having their own internal hot water reservoir.

Lastly modern hot water tanks do not lose a lot of heat.

shazronnie

My combi boiler is so frustrating.... if you run the tap too fast the water cant heat up quick enough. I have to fill the bath really slowly...should i alter any settings?

Cardew

shazronnie wrote: »

My combi boiler is so frustrating.... if you run the tap too fast the water cant heat up quick enough. I have to fill the bath really slowly...should i alter any settings?

You are describing one of the main problems with some combis as it is quite normal at this time of the year to have a lower flow of hot water. This is because the input water from the mains is much colder.

Some have a winter/summer switch.

Possetjohn

Hi have an old combi with a pilot light. It takes quite a while before the hot water reaches the taps, all the while water is running to waste. The new boilers do not have pilot lights so a fan has to purge the boiler, meaning it will take even longer to get going. Is this going to be a real nuisance? and will it be a considerable waste of water.

As mentioned by everyone else there should not be much difference in water waste between a new and old combi.

However often when an existing hot water tank system is replaced by a combi, the existing hot water pipes are 22mm especially running to baths or showers to minimise pressure drop from a gravity feed. When replaced by a combi this pipe size is too large. 22mm pipe holds about 0.38lts of water per meter while 15mm pipe holds about 0.18lts of water per meter. With long pipe runs this is a significant difference in the amount of water to heat before it emerges at the tap etc.

We have this problem and as I refurbish the bathroom/showeroom I will replace all pipe with 15mm and minimise the pipe runs

Cardew

shazronnie wrote: »

My combi boiler is so frustrating.... if you run the tap too fast the water cant heat up quick enough. I have to fill the bath really slowly...should i alter any settings?

I have a combi in an annex with an 82,000Btu(24kW) output.


On winter setting the maximum water flow according to the specification sheet is 7 litres a minute. In really cold weather it probably doesn't achieve that rate.

So an average 80 litre bath will take a long time to fill - even allowing you might mix with some cold water.

frosty_phil

Garsh wrote: »

Hi, I'm new to this so please bear with me - I have a Worcester combi boiler that was completely rebuilt 1 year ago under the manufacturers service contact...and I mean completely. Ot was off the wall and new backplate and all components replaced. However, recently the shower runs hot for about 30 secs then cold for 30 secs and just keeps on doing this - has anyone any ideas as the service engineer can't fix it.

Thanks

I have a thermostat controlled shower which did this when it was first connected to the combi boiler. I cant remember exactly what was going on. It was something to do with the flow rates of the hot and cold water. I think I reduced the cold water flow to match that of the hot water.