Combination tank - little then no hot water.

Have a Telford Direct Combination tank.
Turn on the tap and some hot water comes for 10s or so, then trickles to a stop. Wait a minute, repeat, same thing.
Any ideas what the problem could be?
Thanks in advance, Alastair
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Is there water in the tank?
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Alastair Taylor says...

into the bottom of the hot cylinder. Having had a quick look at a picture on the Telford website this may not easy to fix :(
I had a similar problem with a differnet style of combination tank - In my case it was limescale build up that blocked the bottom entry and I used a bucket load of Fernox poured slowly into the small header tank that was part of the hot water side. It looks like your tank may not have this - just the main cold tank on top?
Peter
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Thanks Peter. Cold tank is indeed on top. Tried pipe unblocker down the feed hole and can feel/hear lumps of limescale moving around at the bottom. Managed to get a good flow for 10 minutes or so, then the damn thing blocked again.
Have tried 2KG DS3 through a funnel, but not having much luck. Will try another dose later. How effective is DS3? Any more aggressive cleaners that are safe with this type of kit? If I cut the supply off from any plastic pipes, is DS40 a good idea?
Alastair
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