Central Heating Question

Hot water does not heat up

I have a Megaflow system with potterton profile boiler and Honeywell 9400 programmer.Up to now it was working fine .After draining the system to add fresh inhibitor , the central heating now only works.The system was plumbed with separate motorised valve for hot water and separate for central heating,If I switch on the central heating switch the central heating does work but if I switch on hot water the water does not heat up. Also while the system was empty, the hot water valve was replaced and wired accordingly by removing each coloured wire individually of the old valve,to be on the safe side for future, even though the one on the system was working. Any idea of what has happened as before the addition of inhibitor the system was working fine ,any advice will be highly appreciated

3 Answers

Best Answer

At your boiler programmer select Hot Water then feel the flow pipework from your boiler to your unvented cylinder (Megaflo) if it's cold then the motorized 2 port valve is not responding, so no heating flow water is reaching your unvented cylinder heat exchanger hence no hot water, suggest you get a competent heating engineer in to fix problem if you feel less confident.

Answered 3rd Mar 2013

Boiler Homecare

Member since 6 Jan 2010

On most valves there is a lever to open the valve manually set the lever open if hot water starts to go through the coil the valve is faulty or wired wrong, if you still have no flow through the coil check the coil is vented of air as this will stop flow through the coil.

Answered 4th Mar 2013

chris tomlin

Member since 28 Mar 2012

Hi Cass,
If you are sure that the wiring is the same as before, then it sounds like air in the system.
Check the pipes going into the cylinder to see if you have any heat on them. When you switch on water on does the valve open up? If the valve opens then it sound like air.
Good Luck


Answered 5th Mar 2013

Duval Heating

Member since 16 Feb 2013

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