Immersion heater replacement - no drain cock

jace_da_face

So my main hot water tank needs an immersion heater replaced. It’s the lower immersion that sits just a few inches from the base. The tank itself, I estimate to hold about 140 liters. The problem is there is no drain cock in place.

I guess that leaves me no choice but to crack open the outlet and siphon from the top to drain the tank. Does that sound reasonable? Any other suggestions welcome.

K.Flyer

Very unusual that there is no drain cock. On the green combination cylinders check that it's not covered with the insulation foam, usually to the left of the immersion heaters. If none then its a hose in through the hot water outlet connection.
If its a Stainless Steel cylinder and the drain is not fitted, the only way is through the connection on the top with a hose.
Hope it helps.

listermint

Why not just open all the hot taps?

K.Flyer

listermint wrote: »

Why not just open all the hot taps?

Because that will not empty a cylinder.
The hot water draw off point is at the uppermost point of the cylinder. When you turn off the water and run the hot tap you will only drain as far as the top of the cylinder, leaving the rest of the cylinder full.

corkgsxr

Take off the fill up high under the valve and connect to that pipe and siphon it from there.

Probably need a 3/4 by 1/2 straight to reduce

jace_da_face

K.Flyer wrote: »

Very unusual that there is no drain cock. On the green combination cylinders check that it's not covered with the insulation foam, usually to the left of the immersion heaters. If none then its a hose in through the hot water outlet connection.
If its a Stainless Steel cylinder and the drain is not fitted, the only way is through the connection on the top with a hose.
Hope it helps.

Ok that's interesting. I figured the drain would have been installed on the inlet pipe by the plumber, and not on the tank itself. If there is one on the tank, well that would be a god send. I'll have to go poking through the insulation with a knitting needle to see what I can find.

jace_da_face

Looking at some images online, the drain often seems to be incorporated into the cold water feed, see 1.. If my tank doesn't have a dedicated drain, I'll be very annoyed one did not get installed on the supply line.

K.Flyer

Sorry, I automatically thought it was a tall combination cylinder, rather than a normal sized cylinder with two single heating elements.
You are right, normally in a set up similar to the image the drain cock is often found on the bottom connection.

jace_da_face

Drat. Do I bother installing one? Probably not.

Wearb

jace_da_face wrote: »

Looking at some images online, the drain often seems to be incorporated into the cold water feed, see 1.. If my tank doesn't have a dedicated drain, I'll be very annoyed one did not get installed on the supply line.

Sometimes i have seen a valve installed on #2 a bit higher up, Higher than the top of the tank. If yours has one, you could isolate the cylinder with it. Then slightly loosen the nut at the cylinder side of #1 and rotate the #2 pipe to create a drain off. Of course, you will need to connect a garden hose or similar to the top of '2.

jace_da_face

Wearb wrote: »

Sometimes i have seen a valve installed on #2 a bit higher up, Higher than the top of the tank. If yours has one, you could isolate the cylinder with it. Then slightly loosen the nut at the cylinder side of #1 and rotate the #2 pipe to create a drain off. Of course, you will need to connect a garden hose or similar to the top of '2.

There is a gate valve in the position you speak of. I have reason in the past not to trust gate valves in general, and not to trust this one in particular. I think I will be replacing this gate valve with a 90 degree lever type. I will need to drain down my attic tank to do this.

At that point I will then drain the immersion tank from the top outlet. I don't think I will try your suggestion as I see it going badly wrong.

This is not the first time I have drained this hot water tank. The upper immersion element went in the past so I partially drained the tank, just to below that element, to replace it. I had to stop working on the tank and come back the next day only to realise the gate valve had really let me down. Drip, drip, drip, all night long, with the outlet on the tank still open. Not pretty.