Hot water pressure drop

[Minder]

Hello

I have recently moved into a large house. The hot water and heating is powered by a Worcester Bosch 28 Cdi combi boiler. The house was renovated about four years ago and the loft space was made into bedrooms. I have had a poke around in the remaining loft spaces and eaves cupboards but haven't found a cold water storage tank.

When running the hot water for a shower, the pressure falls away if any other hot tap is turned on. The flow reduces if the kitchen hot tap is turned on, and falls away to a dribble if the other shower is running.

If all the cold water feeds are coming off the main would this cause the problem with the pressure drop on the hot feed ?

 

[sooey]

That's the way combis work, your one will only give enough hot water for one decent shower, and then only if no other hot outlet is open. There are things you can do to improve the situation but not cheap.

 

[Minder]

Thanks, If that is how a combi works, what type of boiler will give me on demand hot water at any draw off point without such dramatic pressure drop?

 

[sooey]

A combi works like that because it is an instantaneous water heater, what you are asking for would need stored hot water and plenty of it, and would need to either be pumped or mains pressure. Although you could get a much bigger combi which will give better hot water than you have now. But a bigger combi or mains pressure system will rely on having a good enough incoming flow and pressure on your existing supply to work best.