Problem with hot water - indirect coil - post above - some more info

[Ernie Bilko]

(Original text below)

I couldn't get anything pushed through the coil - the combination of the right angle at the start and the friction of the side of the coil means I couldn't get anything in more than about 50cm.

So I connectedted a bypass between the feed and return pipes cutting out the coil and ran the system. Hot water then went right though so the rest of the path is clear and the pump is OK (low speed). So the coil IS blocked - probably sludge.

Any ideas on what I can do or is it a new tank?

**************************** I have an oil fired boiler system with two circuits, both pumped. One drives the rads - which works fine, the other goes to the hot tank. Since September I've had no hot water from the tank. I fitted a new pump but no joy. What happens is this:

When the boiler has been running for a while the feed to the coil gets hot as expected but no matter how long the boiler runs, all day even, the return is always cold. If I switch off the pump I can hear the water "falling" back down almost like the pump has been pushing against a blockage.

So I drained the system and disconnected both ends of the coil and there is standing water at both ends. I would have assumed that the coil would have drained out via the bottom pipe when I emptied the system, is this correct?

Does this all seem like the coil is blocked inside the tank. If so can it be unblocked or is it time for a new tank.

House was built in 1995

*******************************

[Calvin]

By "right angle at the start" do you mean a 90 degree elbow at the

*bottom*. If so then I'd bet my next pint that is where you'll find the blockage.

[Doctor Drivel]

If it is old then replace with s fast recovery coil, not a Part L. I think you said you didn't have access to clear the coil.

[meow2222]

blocked hot water coil: If the tank has a port for an immersion element then a coil can be inserted there and used. Another possible is an external heat exchanger.

[Ernie Bilko]

As a last resort I'm thinking about connecting mains water supply to the coil to try and flush it. What I can't figure is an easy way to connect an external tap or hose to the coil. The tank presents 22mm male connections at the coil (i.e. it mates with 22mm pipe and olive). Is there an easy way to connect to the mains water. There is an external tap on the outside wall - easy distance for a hose. What I can't figure is what sort of connection/union would allow me to connect from a garden hose to the 22mm on the coil.

[Mike Tomlinson]

In article , Ernie Bilko writes

22 to 15 mil adapter, short piece of 15mm pipe, push hosepipe onto 15mm and secure with jubilee clip. Similar arrangement for outlet using hosepipe borrowed from neighbour, end shoved into toilet?

[jsabine]

You *can* treat hosepipe (well, mine at least) as though it's plastic pipe, and get it to connect well enough to a compression fitting, so

15mm insert and straight into the end of the 22/15mm reducer should work.

I wouldn't be inclined to trust it for long, but for this sort of job where it's not unattended it's simple enough.

[Ernie Bilko]

Turns out Hozelock do hose connections with a 22mm thread. Bunged two of these on and used hozelock clip connections for feed from mains water and other end to outside drain.

Turned the water on full whack, a loud "gloop" and black crap went down the drain.

Reconnected and after running the heating for an hour, the return from the coil is nice and warm and the top of the tank is warming up nicely.

Not going to mess with it any more now but come summer I'll dose with X400 or X800 and flush through.

Thanks for all the suggestions, in this case brute force was the solution !!!

[dennis]

Don't leave it that long to add X100 though. They do a descaler you can add and leave in don't they (X300?)