Immersion heater element length

As I took it out I was surprised to

Why did that surprise you? I warned you.

The feed to the hot taps comes out of the hole at the top of the cylinder.

Adam

Another note...

- Alternate tighten/loosen with any stuck nut

- Fit an isolator ball-valve in the CW tank supply

- Check the terminals after 6 months for loosening - Neutral as well as Live

Whilst on the subject of tanks, what is the min height for a combination tank (CW+HW) above a sink/bath tap?

I know that. But, although they were open, water had stopped flowing from the taps. Normally you can draw a fair bit of water from the hot taps even though the supply is turned off - presumably half empty the cylinder! In this case the isolation valve was working ok - although it wasn't to start with - so why was the cylinder completely full when no water was coming out of the taps?

Unless there is a drain c*ck fitted on the cold water input to the cylinder, you will never be able to empty the tank just by running the taps if the hot water comes from the top of the cylinder (as is the normal way of doing things).

Cold water comes into the bottom of the cylinder from the header tank in the loft, and displaces the water from the top of the tank through the hot water output at the top. If there is no drain c*ck fitted, the only way to empty the cylinder is to loosen the cold water inlet pipe and continually mop up the water as it leaks out of the cylinder. If the cold supply to the cylinder and the bath tap are from the same pipe (ideally not, as this would restrict the flow with the hot and cold taps running together), turning the cold tap on would probably drain some of the water out of the cylinder until it drops to the level of the tap.

When I replaced my cylinder, I made a T junction on the cold water inlet pipe just before it went into the bottom of the cylinder. I reduced the outlet to ½" and connected a short piece of pipe with a blanking plug at the end. I fitted an isolating valve between the junction and the blanking plug. This method means that the blanking plug will ensure that there are no leaks, even if the isolating valve is accidently turned on. The isolating valve means that, after removing the blanking plug, I have complete control of the water flow when I want to drain the tank. I then just stick a hose where the blanking plug was and run it downstairs into the garden.

If the isolating c*ck is between the header tank and the cylinder, turning it off will prevent any water flowing into the cistern and the water should stop flowing from the hot tap as you turn the c*ck off. If you only turn off the water at the mains, then you would have to drain the header tank as any water would still be able to flow from the header tank to the cylinder.

Roger

Because you are asking water to flow uphill. Once the headertank is empty or isolated there is no pressure to the tank to force the water out of the top of the cylinder.

Adam

Not sure I have seen those tanks.

Adam

Thanks, I see all that perfectly clearly now. We do have such a drain c*ck, as you describe, already fitted at the cold water supply to the cylinder. Of course this would only needed if the cylinder needs to be replaced. As I have already discovered, the heating element can be replaced without too many problems even if the cylinder is full.

Of course. I was basing my (confused) thoughts on the fact that when we lose our water supply here (a regular occurrence at one time) we can continue to draw water from the hot taps for some considerable time. I realise now that this is simply because the header tank is full and continuing to feed the hot water cylinder.

(S)He may be referring to something like "Harcopak instant plumbing". My house, built 1973 ish, had this when we moved here. In the airing cupboard was an angle iron frame with the cylinder in the bottom half, then a tank above with a small tank in that for the heating feed. Both parts of this upper tank were fed from the rising main, and each had a ball valve in it. I think the house was built round it, when the tank leaked, I extended the pipes up into the loft, put in two plastic tanks, and removed the arrangement below. But even removing the airing cupboard door I couldn't get it out. I had to cut the frame apart with an angle grinder, which of course made me extremely popular.

Steve

I know these tanks as Fortic tanks - I think from the original manufacturer's name. Very popular for flat conversions to save running pipes through upper flats to get to the lower ones.

To the OP: Provided the bottom to the combined tank is above the height outlet tap and the pipe runs are as short as possible then there should be adequate flow as this will give about 3'head. Ideally use 22mm pipe to reduce the frictional losses. Useless for a gravity shower though so either need a pump or easiest and electric shower.

Bob

thank goodness for combi boilers!

Is that because combi boilers never break down?

Adam

Less to go wrong and no worries about get an unintended hot or cold shower from a tank in the roof which gets full of crud, or a hot water tank that doesn't vent properly!! Oh you also get an airing cupboard when yu take the cylinder away!

Also it releases the tanks from the loft for use on the allotment. I now have 6 of them collecting rainwater coming off the shed and greenhouse. Whenever I see the signs of this work going on I stop and see what's been thrown out on the drive or in the skip.

Steve

Cupboard I see, as it is no longer half full of tank. But how does it air?

Andy

We put a small rad + TRV in ours - works a treat.

That said, we also put our cable modem & router plus their associated power supplies in, too, so barely need the rad ...!

More chance of a combi failing than an immersion heater.

If you want the airing cupboard space then put the cylinder in the loft.

Adam

Why keep a tank constantly full of hot water at todays elec prices?

My guess would be 11" as your cylinder is only 36" high. If your element (like mine) is screwed onto the top (curved) surface I would imagine a 27 " long one would foul against the opposite side of the cylinder when fully inserted. My cylinder is approx 4 foot tall and that definately has a 27" element Is it possible for you to get a fairly accurate measurement following the line of insertion, if you see what I mean.

HTH

John