Central Heating Question

Can i continue using a heating and hot water system with a noise hot water cylinder for a few days?

I have a Potterton Promax SL Range boiler with Megaflo Unvented Indirect SystemFit Hot water Cylinder, controlled by a Danfoss TP9000 programmable room thermostat with hot water timer.

Now our hot water works fine but our central heating only works when the hot water is on as well. If we just switch the heating on the light comes on fine on the TP9000, but the boiler does not fire. Because the above problem, we set the TP9000 to switch on the hot water and heating the same time. Today, I noticed a new problem: sometimes the Hot water Cylinder made strong knock voice. I stopped for a while and started the heating and hot water. It worked for a few hours, then, the knocking noise occurs again.

Because I cannot get a plumber to fix the problem quickly, I would know if it is safe to continue using the heating and hot water system for a few days.

2 Answers

Best Answer

Safe to use, as there are several safety features built in to the unvented cylinder if a problem arises if it was installed correctly. I suspect that a diverter valve has failed hence why when you call for hot water only the central heating circuit heats up too.

As soon as the opportunity arises call a heating engineer to attend and diagnose the fault(s) and make good repairs, better sooner rather then later!

Answered 30th Dec 2017

Boiler Homecare

Member since 6 Jan 2010

Your heating issue most probably will be caused by one of these 3 components: room thermostat, programer, 2 or 3 port valve.
If you have 3 port valve in very rare occasions hot water thermostat on a cylinder malufunction which could also affect no heating. It is very rare but the way 3 port valve works, it also gets a signal from water cylinder.
As you have have Megaflo cylinder, that is a bit unique. It requires to have air “cushion” inside cylinder. Check tundish, if you can see any signs of moisture inside of it, then thats why you may have noises from your cylinder coming. That air cushion needs to be replenished with air from time to time. There is normally a sticker on a cylinder describing the steps to perform this task, but is better if you ask your heating egineer to perform that for you as this is a pressurised cylinder and there are a bit more risks involved than with vented system.

Answered 5th Jan 2018

HM Services

Member since 5 Jan 2018

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