Y-Plan Fault

[Iggifer]

I don't really get involved with heating all that much, but I have the problem below in my house

Problem: When controller is calling for HW the rads heat up, despite CH not calling for heat

Components:
Vented System Boiler & HWC
Controller: Potterton EP2000
Boiler: Glow worm Fulesaver 45F
3 Port Valve: Honeywell Sundial Y-Plan

Steps to identify fault (Tested by switching controls from Auto to 24H)

1) Controller set to HW only, room stat off, HW heats, as do rads
2) Controller set to CH only, room stat off, no heat
3) Controller set to CH only, room stat above room temp, CH heats, HW gets warm but not as hot as the rads
4) When operating controller with the cover off the valve head, the HW control actuates the motor but the CH control causes no movement in the motor, either calling for heat or not.

I'm suspecting either a faulty motor or the valve is seized. I'm hoping it's just the head as I can manage that, but I'm not going to just change it for the sake of it

Thanks for any input on anything else to check, or what has failed

 

[john90]

there is a great post in the FAQ's on Y plan fault finding, take a look...
If you have a multimeter that would be helpful, if you are competent on system electrics

 

[john90]

sorry, meant to say Boiler & Central Heating FAQ's section

 

[Iggifer]

//www.diynot.com/forums/plumbing/boiler-central-heating-faqs.175736/#1198061

That the post you mean? Yea I read that prior to posting but that post relates to having one or the other, not both when it shouldnt be

And yes, fully competent with wiring and have a variety of meters, megger, 2 pole fluke, clamp meter and a dreaded voltstick

 

[john90]

not that one, this one - it's on the second page of Boiler & Central Heating FAQ's section - sorry, don't know how to do a link....


Boiler & Central Heating FAQ's section
17) MID POSITION VALVE EXPLANATION AND DIAGNOSTICS

 

[matt1e]

//www.diynot.com/forums/plumbing/boiler-central-heating-faqs.175736/#1198061

That the post you mean? Yea I read that prior to posting but that post relates to having one or the other, not both when it shouldnt be

And yes, fully competent with wiring and have a variety of meters, megger, 2 pole fluke, clamp meter and a dreaded voltstick

you have a wiring fault
The actuator should not motor on hotwater demand, by your description yours does
the actuator should always motor on central heating, by your description yours doesn't

has it ever worked properly?
if so has the programmer,cyl stat or valve head been changed recently?

sometimes for testing its easier if you just take the valve out of the equation if you have a meter,disconnect the valve orange,grey, and white wires from the wiring centre (making a note of where they connect)

(the following refers to where the colours connect not the now disconnected wires themselves)

1) turn on hotwater,make sure the cylinder stat is turned up, leave CH off and measure between neutral and
grey = 0v
white= 0v
orange= 230v
the hot water should be heating at this point,if not and no power on orange trace back through the cyl stat to the hw on terminal in the programmer

2) leave hw on and turn on CH
grey = 0v
white = 230v
orange = 230v
if no power on white trace back through the room stat to the ch on terminal in the programmer

3) turn off both hw and ch
grey = 230v
white =0v
orange = 0v
if no power on grey trace through to the hw off terminal in the programmer (this also has a connection shared with the cylinder stat satisfied terminal)

4)finally to check the cylinder stat,turn the hw back on leave ch off
turning the cyl stat up and down should toggle the voltage between the orange and grey
up = orange =230v grey = 0v
down =orange = 0v grey = 230v

if all of the above checks out then the problems with the valve but I suspect you are going to fail the first test

Matt

 

[Iggifer]

Matt,

Thanks for a comprehensive and helpful post.

It has never worked correctly to my knowledge, the only thing I've changed recently was to replace the T+E that ran from the FCU to the controller as I was moving the FCU but clearly not related & fault was present before and after.

Unfortunately, however, the EP2000 has a built in wiring centre, and to get to the wiring centre, you have to disconnect the controller. Makes for a nice tidy install, but makes troubleshooting somewhat difficult.

Thinking I'll add a length of 3C+E to where the valve head is wired to and then I can test with the controller back in place and will just test L-E instead of L-N

Will let you know how I get on

 

[Iggifer]

Finally had a chance to look at this this morning

Amazingly, it passed all 4 tests.

I too was expecting it to fail at the first test as I don't have very much faith in whoever installed it.

Time for a new valve head then?

Iggy