heating not working but hot water is

Hi all
I have a Worcester 350 combi boiler.
http://s81.photobucket.com/albums/j238/npilcs/?action=view&current=worcester350combiboilerpanel.jpg
The instant hot water works, but the central heating doesn't!
Does that mean the fault lies in the PCB inside; or could someone give us a clue how to sort it?
Thanks in advance.
Regards p.mc
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

http://s81.photobucket.com/albums/j238/npilcs/?action=view&current=worcester350combiboilerpanel.jpg
Not knowing anything about this beast, but such systems usually have a thermostat on the side of the tank which, when it gets hot enough switches over and operates a valve that turns and runs the water through the CH system. The boiler merely looks at the water temp and fires up when necessary.
If the boiler is heating the water correctly then either the tank stat is not working or is wrongly set, or it is working but the divert valve isn't - or of course the pump may have failed. One thing to check is the default setting of the divert valve: does it switch the water to the CH and relax to the tank or vice versa? It should switch to the tank and relax to CH in most systems.
--
Woody

harrogate three at ntlworld dot com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 29/11/2011 08:14, Woody wrote:

--
Bod

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No there's no tank, it just heats on demand. But thanks anyway for the reply.
Any other ideas anyone?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
if this is definately a combi boiler then there are two lots of culprits to check for.
Firstly the heating timeswitch and room thermostat for the radiators...... if both are calling for heating, there should be power at the heating demand terminals in the combi boiler.
Secondly, ther other culprit is the diverter valve, either the motor or microswitch within the actuator has failed or the the diverter plunger has jammed or is leaking internally, due to perished O rings or failed return spring.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi Stephen. Thanks for your detailed reply.
Oddly enough, I only have a switched spur feeding the boiler and definitely no room stat, although the rads have temperature control vaves on (if that is what they are called?) and I presume the "time switch! is the clocky thing on the panel
http://s81.photobucket.com/albums/j238/npilcs/?action=view&current=worcester350combiboilerpanel.jpg So does the below still apply?
--


Regards
p.mc
"Stephen" < snipped-for-privacy@spam.com> wrote in message
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi Stephen. Thanks for your descriptive advice.
We had a problem with low pressure a while ago, shutting off the CH and HW but a fellow came and sorted it.
Yeah the timer was at the right time and the settings are for the kids in the morning.('s got to keep the bills down)
--------- 1...Yes the timer rotates on it's own.
2...The [3] position CH switch was in the off position so I could at least have Hot Water. Because when the CH kicks in it shuts down the boiler alltogether.
3...The timer switch does click when passing the pre-set times. ---------
I turned everything off at the boiler and filled to the red arrow indicator.
I then powered up and set the CH timer to on and also auto. Both times the boiler kicked in. I crossed my fingers, but after a few seconds there was a gurgling sound and the whole system shut down. (should have crossed my eyes also)
I then switched the CH timer switch off again and took a screwdriver and held down the red reset button on top of the unit (silly place!)for a few seconds, which powered the unit once more.
So still got HW but no heating. Better than nothing I suppose
Alternatively...JML Snuggies all round (with impressive free open book light)Bargain!!!
http://www.youtube.com/watch?v=2xZp-GLMMJ0&feature=player_embedded
#!
--

Regards
p.mc


"Stephen" < snipped-for-privacy@spam.com> wrote in message
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
This has in fact been your most useful post in helping me to get much closer to the problem...
see replies inline

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

gave similar symptoms when blocked. I know this is usually down to very cold weather freezing the pipe, but it can also occur from sediment etc. in the pipe.
http://www.worcester-bosch.co.uk/homeowner/customer-service/common-winter-boiler-enquiries
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
P.S is the red low pressure light ON or OFF? its hard to tell from your picture.
If ON, you need to fill the system up with more water. Your pressure gauge's white needle is showing 0.9 Bar thats close to the minimum pressure needed by Combis. Some need at least 0.8 Bar, some need up to 1.5 bar.
Unless someone has fiddled with the red needle, it indicates that you need 1.4 Bar pressure.
There should be a braided metal hose with valves at both ends somewhere near the boiler unless the hose has been removed.
These valves will look like washing machine valves.
Open both taps till the red low pressure light goes out. This will be at around 0.8 to 1.0 bar. then turn off both valves
Do not go any higher than 1.5 Bar or your pressure relief valve (PRV) will open next time the boiler runs. (PRV's open at around 3 Bar.)
Normally, if the system pressure is too low, both hot water and central heating would be affected.
Stephen.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thankfully I do not have a combi boiler but Stephen you have given nice clear fault finding and system explanations so the OP should have no trouble tracking down the fault. Well done.
Gio
--
avast! Antivirus: Outbound message clean.
Virus Database (VPS): 111202-0, 02/12/2011
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On my Worcester, it was the motorised diverter valve. After the engineer changed it, I took the old one apart and it was simply slightly burnt contacts which could have been cleaned.
The diverter comes as a complete assembly at about 105 (for me) but it's only the motor switch contacts that go (apparently)
DG
On 29/11/2011 04:54, p.mc wrote:

http://s81.photobucket.com/albums/j238/npilcs/?action=view&current=worcester350combiboilerpanel.jpg
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sorry for not posting back earlier as I've been quite busy. Anyhow "Thanks guys, you've been absolutely amazing" Special thanks to Stephen for your time and effort.
BTW in answer to your questions:
1...There are'nt any lcd displays or light to show overheating unfortunately. 2...Yes there are trvs open and the same problem occurs.
I think your guess is the right answer, but I haven't got the time to do the neccesary steps yet. Thanks for that Stephen, I'll let you know how I got on when I get the time.
--


Regards
p.mc


"Dafydd" < snipped-for-privacy@spoof.org.uk> wrote in message
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi All
Sincere apologies for my late reply. (Xmas 'n' all) The CH pump was the culprit, there was an electrical feed to the pump so I tried to spin it without much joy. It would turn but wasn't rotating as expected. I'd have had a go at exchanging it, but couldn't find the mains water stop/inline valve anywhere! I looked behind the sink, under the stairs, there were no cupboards or boxing for them to hide in either! (Maybe under floor boards?) So I had to bite the bullet and have a reconditioned pump fitted and...Viola!
Thanks again for all who posted you've been an absolute godsend.
Wishing you all a merry Christmas and happy new year. Regards p.mc
"p.mc" wrote in message
Sorry for not posting back earlier as I've been quite busy. Anyhow "Thanks guys, you've been absolutely amazing" Special thanks to Stephen for your time and effort.
BTW in answer to your questions:
1...There are'nt any lcd displays or light to show overheating unfortunately. 2...Yes there are trvs open and the same problem occurs.
I think your guess is the right answer, but I haven't got the time to do the neccesary steps yet. Thanks for that Stephen, I'll let you know how I got on when I get the time.
--


Regards
p.mc


"Dafydd" < snipped-for-privacy@spoof.org.uk> wrote in message
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

< snip >

So it's all nicely in tune again...?!! :-))
--
martin


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 12/12/2011 21:58, p.mc wrote:

Best intentions and all that..... :-)

So my diagnosis was correct. It would be a burnt out or gone open circuit motor winding.
Shame you had not posted about boiler isolation valves..... I would have told you the answer. Underneath the boiler you will find several valves that are turned with a flat blade screw driver. There are valves for central heating flow, central heating return, cold water in, hot water out and of course the gas isolation valve. Its also in the manual I posted the link to in a previous post.
Once you close the isolation valves, there is a drain cock within the boiler so you can drain just the boiler. No need to drain the radiators or the hot water circuit. You would then be able to replace the central heating pump.
Then you can open the valves, refill via the filling loop, re-pressurise and bleed the boiler, and you're back in business.
Regards,
Stephen.
So I had to bite the bullet and have a

Ouch.... poor wallet. couple of hundred I should think......

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks for the comments.
I did see the man shutting the water off at the boiler as you said Stephen. I had to tighten the drain valve after he left though, as it had a slow leak. I then went around the house and bled each rad, the one in the attic released all the air out of the system and I had to get my daughter to keep the rad valve open whilst i filled the system. When all the air was expelled she closed the rad valve and I pressurised the system to 1.5 bar. Just goes to show though how a little bit of extra questioning can make all the difference...my bad :-)
The sharing of knowledge is truly a great gift.
Regards p.mc
"Stephen H" wrote in message

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.