I have a fully pumped open vent system that's started to heat the radiators when the programmer is set to Water Heater only. I've just changed the 3-port mid position motorized valve (Honeywell V4073) hoping this would cure the problem, but the fault is still there. Help please !
Radiators heating when CH set to Water Heating only
- Thread starter Suffolk123
- Start date
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can only be 3 port valve or reverse circulation.
but you say it has just started.
is the heating pipe from the valve hot/cold when only hw on ?
but you say it has just started.
is the heating pipe from the valve hot/cold when only hw on ?
I changed the complete valve and I double checked that I wired it correctly.
Only a couple of the radiators downstairs appear to be getting hot. The boiler is on the wall in the kitchen and flow goes directly up to air separator, then pump, then 3-port valve in the upstairs cupboard housing the hot water cistern.
The heating pipe a couple of feet beyond the 3-port valve seems to be cool when HW only is on. Does this indicate reverse circulation, and if so what's the best fix ?
Only a couple of the radiators downstairs appear to be getting hot. The boiler is on the wall in the kitchen and flow goes directly up to air separator, then pump, then 3-port valve in the upstairs cupboard housing the hot water cistern.
The heating pipe a couple of feet beyond the 3-port valve seems to be cool when HW only is on. Does this indicate reverse circulation, and if so what's the best fix ?
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if the pipe from valve to heating is cool then sounds like that wasn't the problem.
reverse circulation won't just start after yrs of being ok.
do you know where these rads are connected back in the return pipework ?
can you feel the rads pipework when the heating is on and locate what ones are the flows ? they will get hot first
then feel the rads pipework when the hw is only on then you can tell if its coming up the rads return pipework first.
if so it will be reverse circulation.
reverse circulation won't just start after yrs of being ok.
do you know where these rads are connected back in the return pipework ?
can you feel the rads pipework when the heating is on and locate what ones are the flows ? they will get hot first
then feel the rads pipework when the hw is only on then you can tell if its coming up the rads return pipework first.
if so it will be reverse circulation.
Presumably you did not have this problem originally and decided to change the valve in an effort to cure it.
If changing the valve has not cured the problem then either the valve is faulty or there is a fault elsewhere. It's just a case of locating it.
Here are Honeywell instructions for testing a Y Plan. It assumes you are using all Honeywell components, so you may have to change terminal numbers on stats etc. It also assumes you have wired up according to Honeywell's standard diagram, below.
Cylinder Stat
First of all, make sure you have wired to the correct terminals.
Terminal C (common) is the Left Hand terminal.
Terminal 1 is the Middle terminal -CALL.
Terminal 2 is the Right Hand terminal - SAT
Suspect the cylinder thermostat is faulty only if Terminal 1 does not become live when calling for Hot Water, or Terminal 2 does not become live when satisfied. (Make sure that Terminal C is live in both cases). While checking, disconnect Terminals 1 and 2 to prevent false readings due to backfeed.
Room Stat
1) Remove wire from Terminal 3.
2) Live to Terminal 1.
3) Turn stat to call, if no live on 3 then faulty.
Suspect the room stat is faulty only if Terminal 3 is not live when calling for heat. (Make sure Terminal 1 is live). While checking, disconnect wiring from Terminal 3 to prevent false readings due to backfeed.
Mid-Position Valve
Suspect the V4073A valve is faulty only if the valve does not operate as specified in the following checks (these should be done in order 1, 2, 3, 4, 5 and 6).
Valve open for Heating only
1. Switch off mains supply. Disconnect Grey and White wires from appropriate junction box terminals. Reconnect both Grey and White
wires to permanent live terminal in junction box.
2. Switch on mains supply. Valve motor should now move to fully open heating Port A. The motor should stop automatically when Port A is
open, and stay in this position as long as power is applied to White and Grey wires. When Port A is fully open, the Orange wire becomes live,
to start pump and boiler.
Double check by feeling that Port A outlet is getting progressively warmer.
Valve open for D.H.W. only
3. Switch off mains supply. The valve should now automatically return to open D.H.W. Port B and close Heating Port A.
4. Isolate Grey and White wires and make safe.
Remove cylinder stat wire from Terminal 6 in junction box and connect to permanent live.
Switch on fused spur, cylinder thermostat must be set to call for heat, pump and boiler should start.
Valve open for both D.H.W. and Heating
5. Switch off mains supply. Replace cylinder stat wire to Terminal 6. Isolate and make safe Grey wire and connect White wire to permanent live.
Switch on mains supply, motor should now move to mid-position and stop automatically.
Cylinder thermostat must be set to call for heat.
Both ports A & B are now open for Hot Water and Heating. Boiler and pump should start.
Double check by feeling that pipe outlets from ports A & B become progressively warmer.
6. Switch off mains supply, reconnect White and Grey wires to junction box terminals.
If this check completes satisfactorily, the problem is not the valve, but elsewhere in the circuit.
Programmer
Suspect the programmer only:
(a) After you have made sure that any links required are in place,
(b) After you have made sure that the Programmer has power – to the correct terminal,
(c) After you have made sure that the Programmer timing is set up correctly (see individual Programmer User Guide as appropriate),
(d) If live does not appear at Heating ON Terminal when Heating only is selected on continuous or timed,
(e) If live does not appear at Hot Water ON Terminal when Hot Water only is selected on continuous or timed,
(f) If live does not appear on Hot Water OFF terminal with Hot Water OFF on programmer.
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I've been away for a couple of days so haven't had chance to check out your suggestions.
I hope the new 3-port valve I fitted isn't faulty, but I will check it out in any case as per instructions.
If the radiators are getting hot through the return, what's the likely cause ?
Thanks for your help on this so far.
I hope the new 3-port valve I fitted isn't faulty, but I will check it out in any case as per instructions.
If the radiators are getting hot through the return, what's the likely cause ?
Thanks for your help on this so far.
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