Valve settings on Hot water cylinder

securityforce9

Hi Guys..

Having fierce trouble trying to get hot water to stay in my immersion tank...
Its a pressurised indirect cylinder system (no secondary tank in attic).

Someone fecked around with the valves and I dont know what way they should be set; There are two taps/valves;

1.) Re the tap on the OUTLET pipe of the central heating coil...
A Guy told me this should be open just a 'crack' - but I find if its not open enough, theres not enough flow to heat the water inside - and if its open too much, the minute the heating goes off the content of the tank is stone cold in 5 mins!.....
Anyone know what the ultimate setting should be?

2.) Behind the tank on the cold feed from the attic (to the base of the cylinder), half-way down there is a 'T'-off with a tap, which seems to feed INTO the hot side of the central heating coil pipes as well (not the drain-off tap ). I would assume this is to keep the rads topped up with water? Also on this section of pipe after the tap is the 8ltr pressurised cylinder and the Rad feed.
I've found that if THIS tap is open fully, the same thing as above happens - the heat is flushed out of the system very quickly.
What is the correct setting for this tap?

This is most frustrating, because I know the system is working, only a new install - all Rads bled and no air etc. in system.
Any help would really be much appreciated!
You guys seem to know a thing or two!:)

Sorry if I've posted in the wrong section or anything Mods, its my first post!!)
Cheers

ntpm

By the sounds from your post, your plumber ( or electrician ) HAS NOT zoned your heating and hotwater circuits separatly. ie. you should be able to switch on "hotwater only" and your boiler should be more than capable of heating the coil in your cylinder.
This does not conform to current building regs.... call him back to rectify.

Re: point 1.
The valve is being used as a balancing valve. To split water flow through cylinder coil and heating circuit.
Old fashioned way of doing it. The valve position is hit and miss unfortunatly. I normally keep it around half way. The more you open it the majority of heat will pass through it and your rads won't get as hot!!
I am assuming you do not have a cylinder stat operating a motorized valve (or zone pump) then the likelyhood is that water may be being drained or circulated back through the coil which could be causung the cylinder to cool back down.

Re: point 2.
Sounds like you have a "sealed" heating system.
There should be a pressure gauge near the expansion vessel or near the "tap" or valve. This should read around 1-1.5 Bar when heating is cool and will raise to around 2 Bar when hot.
There should be a pressure regulator fitted after the tap and this should have been set to top up the pressure when required ( not on a regular basis).
You should NOT keep this valve open all the time. You will not know if the system has a leak and you could be introducing fresh water into the heating system which will cause corrosion and sludging.

securityforce9

Many thanks for that, NTPM...

Yes, it is a sealed system.
Unfortunately the company who did it for the builder were the plumbers from hell.
There is no gauge anywhere on the system. There is an 8ltr pressure tank in the pipework beside the HW Cylinder followed by a pressure release valve further along (This has a tiny little 'screw-cap' on the top of it?).

Re the balancing valve;
There is a motorised unit in the pipework coming from the cylinder (en route towards radiator distributor) - this is operated by a room thermostat outside the door.
Incidentally, this motor is not working and I removed it from the pipe about a year ago to replace, but a local plumber told me it wouldnt make any difference without it, as the valve on the pipe would be permanently open, just meaning that I had no way of controlling the temp of the upstairs rads (I just turn off heating when upstairs is hot enough).

Now you have me thinking... maybe this actually HAS something to do with the water in the cylinder getting cool too quick??!
Maybe when the heating is off, the rads are drawing all the heat out of the pipe? (But then again the pump is off too, so I can see how that would be the case).

Cheers.

ntpm

You could be possibly getting natural convection/ gravity flow through cylinder pipework even the pump is off.... hard to tell.


Get a plumber/ experienced heating engineer to check it out and replace motorised valve head.

Seems that the boiler controls are not wired properly as the motorized head should be wired to switch on/off boiler when the room stat calls for heat.