Heating and Hot Water or Hot Water only, not Heating only

N

newnhambolton

Joined
27 Jan 2008
Messages
57
Reaction score
0
Country
United Kingdom
Just moved into a new house and the heating doesn't seem to come on unless the hot water is also on. I wonder if the problem may lie with the programmer which is a Honeywell ST699B or is it the 3 port valve?

If I need to replace the programmer can anyone recommend one that would do heating on its own without having to heat up a tank of water.

Thanks
 
Sponsored Links
sounds like a valve issue.

hw on its own works ok ?
just heating on its own won't work sounds like a faulty m/switch in the valve.
 
Or in your case, the wiring may never have been correct.
With HW and CH both off, there should be 240v on the valves grey wire.
If that is there then a replacement head is the answer.
The valves movement depends on two sources of power. The first is through the room stat and white wire for the first half of the range and in your case thats ok. The second is from the programmer together with one from cylinder stat and feeds the grey wire, for the second half of the range.
So you need to check the voltage on the grey before anything else.
 
As said you need to check you have a connection to the HW OFF on the programmer, if the grey wire is wired only to the cylinder stat satisfied then that can cause this situation.

CH only = 240v on white/orange/grey
HW only = 240v on orange
Both = 240v white/orange and 'break' voltage of 50-110v on grey to hold in mid-position
 
Sponsored Links
D

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

 
You must log in or register to reply here.
Sponsored Links

Similar threads

T
Boiler only firing for hot water, valve not moving
Replies
6
Views
249
Tryingit
T
P
Hot water AND heating when only hot water selected
Replies
5
Views
1K
poobarr
P
V
Central Heating
Replies
1
Views
512
GPlumb
G
R
Darned that control system
Replies
2
Views
481
RP61973
R
B
No control over hot water from central heating.
Replies
4
Views
1K
barrata
B
Back
Top