Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing Fault

[plumbandplumber]

My sister told me that her hot water isn't really getting hot any more (heating is fine) - suddenly it's barely luke warm. I know her system is a bit of a mare, so yesterday posted a question re changing her motorised valve on bungs -



http://www.ukplumbersforums.co.uk/central-heating-forum/71739-changing-3-port-valve-bungs.html



Anyway, went to her house to investigate, expecting to find mot. valve(s) - and there are none. Looks like it's gravity hw on one set of 28mm f and R from boiler, and pumped heating on another F and R from boiler.


The system - Ideal E type boiler, conventional system, 2 tanks, gravity hw, pumped ch, modern Horstman programmer, room stat.



So, boiler fires up for ch and heats rads perfectly. There is power from the hw on terminal in programmer to the terminal block inside boiler and when hw is turned on, the boiler starts and runs fine and after a while cuts out on it's own stat, but it's only heating the bathroom rad which is also on the hw circuit. I opened a bleed valve on a rad and there is plenty of water coming out.



Looking like the boiler and programmer are fine, but have lost nearly all gravity circulation to cylinder, but still heating the bathroom rad.



Help very appreciated - I'm confused. :confused5:

 

[REDSAW]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

ballancing valves choked up open it some more!!

 

[Whyme]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

If its tripping on the boiler stat its restricted somewhere cos gravity relies on a nice big clear pipe to get rid of the heat. there may be air in the coil (higher than bathroom rad pipes)or sludged up.Wheres the vent on the system?

 

[stevetheplumber]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

check the f and e tank if the ballvalve has frozen in the up position the hot water will be the first to stop working 9 times out of ten it will be this

 

[plumbandplumber]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

ballancing valves choked up open it some more!!

Thanks, but can't see any balancing valves.

 

[plumbandplumber]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

If its tripping on the boiler stat its restricted somewhere cos gravity relies on a nice big clear pipe to get rid of the heat. there may be air in the coil (higher than bathroom rad pipes)or sludged up.Wheres the vent on the system?

Thanks. Difficult t tell where vent is, but there's a 15mm pipe teed into flow just before it enters cylinder. Could this be it?

Someone recommended running boiler for a few mins with it's stat removed to blow out crud or air lock. Will this work?

 

[plumbandplumber]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

check the f and e tank if the ballvalve has frozen in the up position the hot water will be the first to stop working 9 times out of ten it will be this

Thanks but plenty of water in system.

 

[jase158]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

best thing to do is drain down, make sure f and e empties. clean out f and e, then fill up with chemical in system and leave for 4 weeks with heating on. much better on these systems then powerflushing IMO

 

[jase158]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

if f and e doesnt drain then you have blockage in cold feed, usually where the 15mm meets the 28mm. cut it out (loads of towels and an iso valve needed!!) stick iso valve on the 15mm, (without getting too wet) close it, unblock pipe with screwdriver or something similar, connect pipe back up, fill system and add chemical to clean out properly.

 

[lame plumber]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

Thanks. Difficult t tell where vent is, but there's a 15mm pipe teed into flow just before it enters cylinder. Could this be it?

Someone recommended running boiler for a few mins with it's stat removed to blow out crud or air lock. Will this work?

video pics please, not for the novice

 

[Whyme]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

Thanks. Difficult t tell where vent is, but there's a 15mm pipe teed into flow just before it enters cylinder. Could this be it?

Someone recommended running boiler for a few mins with it's stat removed to blow out crud or air lock. Will this work?

Dont run it with stat out cos it will just kettle, bang and flirt boiling water over the vent and possibly stress old joints (a very dodgy, old, crude way of removing air). 15mm is normally the cold feed. vent should be 22mm.

 

[Whyme]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

have you tried back filling it, if indeed its air. if that dont work its got to be muck cos it aint circulating..

 

[Best]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

Did you check that the ball valve on the expansion tank is opening to let water in when you drain some off the system somewhere?

 

[stevetheplumber]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

Dont run it with stat out cos it will just kettle, bang and flirt boiling water over the vent and possibly stress old joints (a very dodgy, old, crude way of removing air). 15mm is normally the cold feed. vent should be 22mm.

old and crude works sometimes

 

[Whyme]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

It certainly does but can naff up joints in the boiler and pipework though.

 

[kris]

Re: Thought I should Change Sister's 3 Port Valve - but doesn't have one- Confusing F

It sounds like an older system and the 28mm pipes will be well furred up if the systems never been cleaned or flushed especially if the little tank in attic hasnt had its hat on (lid), if your struggling its best to call in help as depending how bad it is a simple flush might not do the trick, i would slacken the return nut on the cylinder coil to see what comes out , ( i know water but at what colour n speed), or it might be a simple air lock in the 28mm coil pipes,