Combi boiler, hot water takes long time to run warm.?
Question:Combi boiler works great for heating but for hot water I have to fill about 2 sink fulls before it runs hot. The boiler is in the loft space.
Answers:
There might be several reasons ,but this happened to me ,and in my case it was the heat exchanger unit causing the problem.The heat exchanger does what it says,it transfers heat from the hot water from the boiler to the tap water.In my case the tubes in the exchanger were clogged with silt and debris from the heating system and radiators. It is a bit of a job to remove the heat exchanger box from the boiler ,and then take it to a sink and flush it out.Takes a bit of a time to clean it out properly.Once cleaned and refitted my water was fine. Unfortunately the same thing happened about 6 months later.My heating man said that there was a lot of silt and debris in my heating system and recommended a power flush of the whole system. This involves draining the whole heating system and flushing with a powerful pressure until it all runs clear. At first the water was a dirty muddy colour.Clean the exchanger again. refit it all.refill the system,add an inhibitor and it has been fine for nearly two years now Have not needed the exchanger cleaned since.This may be your trouble if the system has been in use for a few years.
it could be silt in the pipes but dont forget if the boiler is in the loft the water has quite a long way to travel down to the sink the boiler takes a few seconds to heat the water anyway so it will take a while to get hot water to the ground floor does it still take a long time to get hot water in the bathroom if it does call out a plumber you can get plumbers with no call out charge but dont just call one get at least 3 then you will know if any are overcharging
Debris in the system is one possibility, but would not be if plumbers ever decide to clean a system when they install, you dont say what type of combi, and some have a pre-heat system, this could be faulty, the flow switch or diverter could be sticking, the fact that it is in the loft (which is not a good place to install a combi) is usually more of an issue in winter, but is combatted by the fact that your heating would be on and therefore pre heating by default, so, was it ok in the winter? 40 seconds is average for a combi to send water to downstairs in summer!
Need to know what type of boiler it is, and what any other symptoms there are. Does the boiler light when you turn the tap on, or is there a dalay. I just had a similar problem with a Vaillant turbomax, and this was the aquastat.
You best coarse of action is to either call the manufactureres tech help line or go on the Corgi website and look for an engineer near you
pipe runs r to long( kown as dead legs)
either move appliance ,which is what is needed, or try to reduce heat losses from pipe, insulate.
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