Worcester Highflow 400. No central heating . Hot water ok.

Joined
18 Dec 2008
Messages
13
Reaction score
0
Location
Ayrshire
Country
United Kingdom
I have a Worcester Bosch Highflow 400.
The pump seems to be working ok. I removed the head and the impellor is still attached and spinning freely. Both the inlet and the outlet from the pump heat up.
I removed the diverter valve and part stripped it. There was a few bits of dirt in it but not much. The diaphragm at the back seems ok.
I'm at a loss as to the reason so any help would be most appreciated.. Thanks.
 
Sponsored Links
Joined
24 Mar 2004
Messages
639
Reaction score
14
Location
Tyne and Wear
Country
United Kingdom
First you need to know if there's a demand for ch. Turn the ch to on at the timer and turn the dhw thermostat down as far as it will go. You need to access the PCB and look for connector X12, it's the one the timer plugs into. You need to have 240v AC across the top and bottom wires. If you aren't getting 240v AC and the red light on the front of the timer is on for ch then your timers gone. If you are getting 240v AC then you need to check whether you are getting 240v AC at plug X7 on the PCB. If you are getting 240 there then the problem isn't electrical. Lots of engineers even miss this one, there's a small copper pipe goes from the diverter valve to up behind the pump. Drain the boiler, remove the pipe and make sure it isn't choked up. You may also want to stick something into the holes it goes into on both sides to make sure they aren't choked either. Any blockage in this pipe will stop the diverter from going into ch mode. If all of the holes and the pipe is clear then I would say your diverter is gone.
 
Joined
18 Dec 2008
Messages
13
Reaction score
0
Location
Ayrshire
Country
United Kingdom
Thanks for the information. Tested ok for voltage at both test points.
Any ideas as to what resistance should be through the divereter coil?
This one reads 2 Meg Ohms which seems to me awfully high.
There is a magnetic pull at the coil though.
Thanks....
 
Joined
4 Jan 2008
Messages
797
Reaction score
0
Location
Edinburgh
Country
United Kingdom
First you need to know if there's a demand for ch. Turn the ch to on at the timer and turn the dhw thermostat down as far as it will go. You need to access the PCB and look for connector X12, it's the one the timer plugs into. You need to have 240v AC across the top and bottom wires. If you aren't getting 240v AC and the red light on the front of the timer is on for ch then your timers gone. If you are getting 240v AC then you need to check whether you are getting 240v AC at plug X7 on the PCB. If you are getting 240 there then the problem isn't electrical. Lots of engineers even miss this one,

Easy way for this, switch everything off on the timeclock, put HW stat to zero and wait for the pump to stop over running.

Switch on CH....does the pump run and the boiler fire for a short period, if so clock and external room stat is working.

Diverters are problematic, never had the little tube choke although it is a known problem, after these if still not working then there is a filter in the top manifold that can block also.

My money would be on the diverter valve.

when replacing make sure you put the small thin o ring only on the first shoulder of the central plastic tube and not fully home.
 
Sponsored Links
Joined
18 Dec 2008
Messages
13
Reaction score
0
Location
Ayrshire
Country
United Kingdom
Thanks for the information folks.
I've ordered a diverter valve so it's big jumpers and jackets time till it arrives.
I'll let you know how it goes......
 
Joined
18 Dec 2008
Messages
13
Reaction score
0
Location
Ayrshire
Country
United Kingdom
Diverter valve arrived on 24th Dec. Fitted it and the heating started working. Woke up on 25th and it was back to the original problem.
Went to Tenerife on 26th and just back today so i've beeen warm for a week at least.
I've not tried to clean out the filter mentioned on an earlier post as I'm not sure exactly where it is.
Again, any help would be gratefully appreciated. Cheers.
 
Joined
24 Mar 2004
Messages
639
Reaction score
14
Location
Tyne and Wear
Country
United Kingdom
when you had it drained down for changing the diverter did you check the little tube I mentioned in my post?
 
Joined
18 Dec 2008
Messages
13
Reaction score
0
Location
Ayrshire
Country
United Kingdom
Yes. The tube was fine.Took it out,blew it through ok and checked ports on either side.
 
Joined
18 Dec 2008
Messages
13
Reaction score
0
Location
Ayrshire
Country
United Kingdom
Ended up getting a heating engineer in today.
Gave him the story so far, & he started checking things then eventually said he was stumped & reckoned the new diverter valve must be goosed.
He fitted another new one & fingers crossed it's been ok now for 3hrs.
Many thanks for your help weargas & superduper.
Cheers.....
 
Joined
27 Dec 2010
Messages
1
Reaction score
0
Location
London
Country
United Kingdom
did you ever find out what was wrong? we have exactly the same problem. plenty of hot water, but no central heating. and no error messages. we had diverter replaced about 3 weeks ago - worked fine for a while, but back to the problem in past two days. any thoughts?
 
Joined
29 Oct 2015
Messages
2
Reaction score
0
Country
United Kingdom
Had this exact problem - Changed the diverter valve - £53 as the old one did look full of gunk. Cleaned the small diverter pipe, again this had some debris in there. Assembled everything back together and the heating did seem to work for a little bit of time, but then nothing again.
Left it a few days, and filled a radiator with flushing agent... still nothing.
Took of the coil from the diverter to see if it was being energized by the system when running on heating and yes it was - tested by holding a screwdriver to it and feeling the magnetic pull and then no magnetic pull when the heating was switched off. So this means the diverter value was not being engaged even though the coil was working. So at this point I stripped out the pump and removed the diverter flow pipe again... Only this time I pushed a small star screwdriver up through the connector where the pipe fits into the flow from the heat exchanger and out popped a plug of debris. After fitting back the small diverter pipe and pump, started the system again and hey-presto instant water flow to the radiators and HEATING AGAIN :) - System is working better now than it has for years.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top