Inconsistent hot water supply from thermal store

A few months back I posted a problem ive been having with my water syste where the immersion heaters were working and the water tank was storing hot water without problem. The system is a flowmax 180 thermal store

The big problem was getting the hot water out of the tap. I could get hot water flow only for about 10 seconds before the flow went cold. If I turned off the tap all together wait a few mins then turn it back on the same thing would happen, a flow of hot water for a few seconds then it would go cold again.

I called someone out to have a look at the system and the said the t-stat on the E7 water heater had gone so that was replaced so after that the system seems to produce and store more hot water than before.
However I’ve still got the same problem of the flow of how water being very inconsistent where it will flow hot then cold and sometimes back to hot again if im lucky.

Typical example is trying to run a bath just now. With the hot tap fully open I got a flow of hot water for a few seconds then it went cold. After messing about with the hot and cold taps in the bath tub and the bathroom sink, turning on both hot taps or one hot one cold at the same time etc... I finally got a steady flow of piping hot water from the bath tap(after about 10 minutes). This was with the bath tap about half open. Once the bath was nearly full I opened the hot tap fully and the flow quickly went cold again. Turned it completely off for a few minutes, then back on only to get a constant flow of hot water again. There is definitely a store of hot water to be used, its being able to make use of it consistently.

After messing about with the taps for ages it is possible to get hot water but Im planning to rent the property out so ill need to get the problem resolved fully.

Does anyone have any suggestions as to what it could be and what options I have to get it repaired, like I said, the system is creating hot water so It would be good to know what options I have

In my previous post a few people suggested it could be a problem with the blending valve... is that an expensive repair or would I better of just replacing the whole system as this one has never been right.
Any advice appreciated.

sounds like the blending valve on the hw pipe that mixes with cold to control the water temp at tap. cheaper to replace that than whole system.

First port of call is blending valve, quite easy to test. If not scaled coil, both will cost less than a rip-out

Looking at the MI's as a pdf, the filling of the thermal store appears similar to a boilermateII.

Check your water level, but, if like a gledhill the base of the vessel is sludged up, you may need to unblock the cold feed (thats the pipe from the base of the tank on the top) and the water level has dropped sufficiently to uncover the coil. A piece of stiff wire may clear it, safer may be to gently, blow water down it from the mains inlet pipe (a short length of garden hose will be useful), then note if water level drops in the tank on the top with the ball valve held in the closed position.

disclaimer, this advice is free, no responsibility accepted if things do go t*ts up.

DH

thanks for the advice guys.

So starting with the blending valve, can you tell me how to locate this part and what prodedures i need to do in order to test it?

thanks

Rob, try here for more info http://www.range-cylinders.co.uk/pdfs/technical/flowmax.pdf

You can then see all the components.

DH

Hi, I have recently moved into a house with a flowmax thermal store. I have EXACTLY the same problem as you had. Did you ever find a solution? If so, can you let me know how to fix it?

Thanks...

drmark said:

Hi, I have recently moved into a house with a flowmax thermal store. I have EXACTLY the same problem as you had. Did you ever find a solution? If so, can you let me know how to fix it?

Thanks...

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Have same problem at the moment flowmax tank 30 secounds hot water changed blender valve at £70 no differnace, now as we write flushing with fernox DS3 DE SCALER tank seven years old and the secound one I have had.

If this dont work. it means I think bad design on the internal coil or blocked