Draining Hot Water Cylinder

[RolandK]

Hi,
I need to drain a hot water cylinder heated only by twin immersions. Can I do this by turning off the mains so that the cold tank does not refill and drain the lot through the hot taps. That is drain the cold tank first then the cylinder?

Thanks,
Roland

 

[tackleburger]

That will only drain down the cold tank wich you may need to do unless you can isolate the cylinder feed from the tank.

To drain the cylinder you should have a drain off at the bottom where the tank feed is. If not, turn off cold supply at mains and drain cold tank via hot taps or isolate and drain system via hot taps. Once you are sure hot supply is off open top connection on the cylinder (a wee bit water will be in the pipe) get a hose in the top measure to the bottom keeping you finger over the other end take it to a suitable point below the cylinder outside or a sink below will do. Suck on the hose and water will syphon out the cylinder. Then wait and the cylinder will drain.

 

[RolandK]

That's great, thanks a lot

Roland

 

[arhplumbheat]

Install a doc and gate valve on the cold feed so you dont have to do all this again if you need to swap a heater or get a leak.

 

[joe brown]

It should just have a drain valve at the bottom, Cant see why it wouldnt.

 

[pauls]

i know you shouldnt but id prefer a lever valve over a gate valve much better

 

[tackleburger]

Gates are crap really. Come across them all the time on unvented cylinder feeds. As good as useless. Why can't you use a lever, a full bore one is perfectly acceptable.

 

[charlie frederi]

Yeah make you right there full bore lever valves rule

 

[flyboy]

I have just had a system installed and no drain cock was fitted at the bottom of the HW cylinder. Well it might have been but as the bottom inlet is at the back and the pipe rises straight up you cant see it, or get at it. Do the regs say you should have a drain cock for the cylinder in new installations?

 

[not got a clue!]

HI, I really really could use some help. We live in a top floor cottage flat. I have just bleeded my radiators and now we have no hot water and no heating. My missus said this happened to her before and when she had it fixed she was told it was a lack of pressure which I presume was due to the pressure lost through the radiator valve. I checked the pressure gauge at the cylinder at it was at 0. I opened the tap at the gauge to get the pressure to 1.5 bar. The situation is still the same. I think the cylinder is empty as it sounds so when i tap on it, but I do not know how to fill it. We don't have a combi boiler if that helps. Any advice on how to fix this would be very much appreciated, thanks. Steve

 

[raymondo68]

Hi there

does water come out of the hot taps if you open them? If it does then the cylinder is not empty.

Have you checked the boiler for a reset? Maybe switch of at the main switch for 5 mins and then on again.

raymondo

 

[raymondo68]

flyboy

In the circumstance you describe the drain off is normally extended around the base of the cylinder using 15mm copper tube. If this has not been done you should really get the guy back and make him install it!!

good luck

raymondo

 

[Alpha man]

flyboy

If this has not been done you should really get the guy back and make him install it!!

good luck

raymondo

Yeah right!!, if he couldnt do it right in the 1st place, what makes you think he'll come back and fit a DOC!!

 

[not got a clue!]

Thanks for replying Raymondo. I was talking nonsense apparently about no water in cylinder as water does come through the taps and I have now had a look from a ladder and can see water in the top part of the cylinder. I have just noticed that some of the 22mm pipes next to the tank are hot although still no hot water or heating, does this mean an airlock? I am going to go and try to reset the boiler as you suggested. Thanks for taking the time to reply. Steve

 

[Reg Man]

All hot water vessels require a method of draining down (Draw off Cock). This should be located normaly on the bottom cold feed inlet.

Question over gate valves and full bore lever valves? Does anyone know where it says you cant use a full bore lever valve on a cold water feed to a hot water vessel? If they are not allowed its got by me.

 

[raymondo68]

not got a clue

from what you have just posted, I think you may have what is known as a combination cylinder or a thermal store. a photo would help.

If some of the pipes are getting hot and would suggest that the boiler is working fine but that you do have a circulation issue, again a photograph(s) of the cylinder and associated pipework would help.

regards

Raymondo