CH Help/Info

[Bread]

Hi, I'm not sure whether i'm after help, advice, reassurance or all three here so bear with me.

I have an old Glow worm space saver 20-30 F boiler. A honeywell 4073a 3 port valve, honeywell cylinder stat and honeywell room stat. (y plan?)

The HW is gravity fed and CH is pumped.

If I have programmed for HW & CH to come on for 4 hours for example, the hw will come up to temp (60deg) fine BUT this will then cut out the CH. This applies even if the room stat is set at 30 deg. The CH seems to come back on again when the HW has reduced in temp sufficiently for it to called for again. It's as thought the room stat has no bearing on the CH staying on. As long as the orange light on the room stat is on the CH will come on with the HW (when both are called for). The orange will click on at approx 10/15 degrees.

From reading the forums it appears that with gravity HW & pumped CH you can only have them together but should the CH not continue as long as both are on at the programmer even though the HW has been satisfied and the room stat is set at 30? Or does it run on a cycle whereby the rads heat up/cool down in line with the HW demand?

The 3 port, cylinder stat and room stat have all been replaced from the originals (all 20+ yrs old) in the last couple of months but the result is the same.

When the HW has been satisfied the 3 port doesn't seem to move over to leave port A open. If i have programmed the HW & CH to both be on but the room stat turned right down, the HW will heat up to temp fine, then when I turn room stat on/up the pump will turn continue and the boiler will fire but the valve won't move to open port A only.

It's now got to the stage where it is annoying me because on very cold nights the house warms up a treat but will then become chilly until the HW is demanded again.

Is there a problem with the wiring or am I expecting too much from an old (22 years) system?

 

[compheat]

It sounds to me like you've got a fully pumped system.

if you had a S plan using 2 separate zone valves then you could have gravity hot water, and pumped heating.

The fault could be with the cylinder stat its the way they are wired and can effect the heating

 

[Bread]

thanks,

Not fully pumped as I have F & E tanks in loft.

The cylinder stat only has 2 wires going in to it if I remember correctly, so not much to go wrong there?

 

[compheat]

Not fully pumped as I have F & E tanks in loft.


The F&E tank as nothing to do with being a fully pumped system.

I think you are referring to a sealed system. and if your cyl stat only as 2 wires which will be live in and live out then its not wired for a 3 port valve.

 

[Bread]

Ah.. ok. I assumed that the F & E tanks made it grav HW and pumped CH.

My apologies, just checked and it's 3 wire to cylinder stat. Doh! They all match up with the correct no's in 10 way box according to honeywell y plan drawing.

 

[johnnojob]

ok with heating and hot water heating up,dont leave it get to hot to soon.
turn down cylinder stat till a click is heared,the boiler should stop fireing for a short time like 30 seconds them the 3 port should have to motor accross to heating only and re fire the boiler.
dont confuse pump noise for boiler fire as some systems pump is live independent.

how long you lived there ?.

wired up wrong.

3 port valve sounds faulty.ie seized or micro sw not activating heat only.

read posts here and the answer is there.

 

[45yearsagasman]

You have a fully pumped Y Plan system,and you should be able to operate hw and ch together and independantly.There is a very good explanation on the forum FAQ's of the working of a Yplan setup written by D.Hailsham which tells you all you need to know.If you have some electrical skills you should be able to find your fault.If as you say the 4073 was just replaced I would not suspect mech fault.Check your control wiring,or better just get a heating engineer with system wiring skills to check it out.If all components go back to a wiring centre then its wiring by numbers and faults are simple to trace.