Primatic Cylinder Fault

[tidder]

I have a Primatic cylinder system with no hot water shut off valve fitted. I needed to change a hot water tap washer. I Shut off the hot water by opening a hot water tap then putting a tennis ball in the header tank outlet This was effective. After the job was completed I removed the tennis ball, then closed the tap. Everything seemed fine, until central heating was needed. The two upper most radiators are warm at the bottom, but cold at the top. I opened the bleed valves on both, but no air or water is expelled, they will not fill. Apart from draining and refilling the system, not a good idea in midwinter, any other ideas would be appreciated.

 

[GasAid]

Drain; refill and bleed off whilst your system is filling... You should only need to drain through your hot tap again; just so you can break the air trap and allow the ch to fill again.

 

[namsag]

Be careful when workin on primatics if you block the cold feed and the open vent at the same time and draw water off either from hot tap or the heating the cylinder will implode..........Yeah agree with your comment below croydon it`s just there is more chance of someone bunging a primatic.

 

[croydoncorgi]

Same applies to ANY cylinder with a (blocked) vent and water being drawn off at some distance below the cylinder!

 

[tidder]

Thanks for all the helpful tips. I have had to wait for a warmish day at the weekend . I tied up the ballcock then turned on the hot water until it stopped. Opened the bleed valves on upper radiators an slowly refilled the system , joy! Each radiator filled OK
Sadly after a couple of hours the system was as before. I think I will have to drain the whole system.
Question: how does one replace a hot tap washer if there is no shut off or service valve?

 

[Nige F]

let the hot stored water cool.........then take the tap apart live with someone holding rags over it while you`re fiddling with the washers

 

[Paul Barker]

Or just do what I do, get aprentice to hold rag over top ducting water flow round tap while you change washers, but also run other hot taps.

Usually this is quicker than going into loft to bung the tank, and anyway it's fun to live dangerously.

Changing thermisters, see if you can get a good enough jet to hit apprentice who is blocking your light, before you introduce new thermister, obviously protecting pcb with a towel, and dodging the flow yourself. best in lofts kitchens or bathrooms to do these aprentice wetting exercises. Clients tend to not like system water on the living room capet.