Why poor hot water supply?

[al shookup]

Three years ago I decided to switch from an under floor gas warm air system to a modern radiator system. I had installed a Worcester Bosch 38CDI Classic Combi feeding eleven radiators of varying sizes. I live in a fairly large bungalow and whilst the heating side is acceptable I am very disappointed with the supply of hot water from all three hot water taps in the property. Whenever I want heated water I have to run off what seems to be a large amount of cold water first. The nearest tap to the boiler is only about four foot away as the crow flies but even then you have to wait forever. The consequence of this poor system is that you forever wash your hands in cold water. According to the service instructions you can select a pre heat by pressing the ECO button on but not have it illuminated. Still no improvement however. Any ideas as to how to improve the current problem please?

 

[Deleted member 120897]

That’s a problem for a lot of systems, not just combi’s. However, with a combi, they do tend to have a lot drawn off before getting hot. Are you’re pipes insulated?

 

[Timmy D]

Turn a hot tap on and time how long it takes for the boiler to fire up. It should be no more than 5 seconds.

If it is under 5 seconds, feel the dhw pipe under the boiler and as soon as you notice it start to get warm, collect the cold water run off at the tap in a bucket.
Collect the run off until the water at the tap gets warm.
Then measure the run off in litres.

Let me know the litres and we can roughly work out how much pipe you’ve needed to empty to get hot water.

Obviously without looking it’s hard to say, but if it’s happening at all taps, it’s quite possible that when converted to a combi/dhw tank removed, a lot of the old pipework was left in place and joint together.

The hot water could be travelling up to where the old dhw cylinder was before being distributed around the property.

Got any accessible pipes in the old airing/cylinder cupboard? Got any pics?

If you find pipes, do not run hot water for a few hours, to ensure the pipes are cold. Then run a hot tap in kitchen/ground floor, see if the pipes further away from the boiler/tap get warm before the tap gets hot water. Then you know it’s taking the long way around.

 

[al shookup]

Turn a hot tap on and time how long it takes for the boiler to fire up. It should be no more than 5 seconds.

If it is under 5 seconds, feel the dhw pipe under the boiler and as soon as you notice it start to get warm, collect the cold water run off at the tap in a bucket.
Collect the run off until the water at the tap gets warm.
Then measure the run off in litres.

Let me know the litres and we can roughly work out how much pipe you’ve needed to empty to get hot water.

Obviously without looking it’s hard to say, but if it’s happening at all taps, it’s quite possible that when converted to a combi/dhw tank removed, a lot of the old pipework was left in place and joint together.

The hot water could be travelling up to where the old dhw cylinder was before being distributed around the property.

Got any accessible pipes in the old airing/cylinder cupboard? Got any pics?

If you find pipes, do not run hot water for a few hours, to ensure the pipes are cold. Then run a hot tap in kitchen/ground floor, see if the pipes further away from the boiler/tap get warm before the tap gets hot water. Then you know it’s taking the long way around.

Thanks for advice.