Hi for a few years now we have not had our c/h working that well and was always told that it was the programmer well I got it changed today we have a gravity system now we cant have the c/h on with out have the hot water on but the problem is as soon as the hot water is fully heated it switches off which means no heating normally bout 1 hour to 1 and a half so the radiators downstairs barley get hot before it switches off, so is there anything I can do about this coz dont think I can go through another cold winter like this thx.
C/H turns off
- Thread starter gman2050uk
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Sounds like the pump isnt working. HW side will work under gravity circulation, but CH will rely on the pump to circulate the water.
I wish it was that easy when we had plumbers in about 2 years ago they said we needed a new pump which works fine you can hear it going and feel it working but just switches off with when the water is hot enough.
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The pump switches off? Are there any motorised valves fitted?
E
expertgasman
After trying to decipher the gobbledegook first post, I think you mean that the problem has always been present. That being the case, I think this is a simple wiring mistake. is there a room 'stat? What model is the programmer. I thionk the orinal plumber was wrong, and this is such a simple system, I or most of the guys on this forum couls identify it in less than 10 minutes.
Hey thx for all the replies it has a motorised 3port valve and I have a Horstmann 425 Tiara Programmer.
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So its not a gravity, but a fully pumped system
Id check the operation on the M/Valve / wiring as it sounds as though the closing sequence to the valve has not been wired.
Mr. W.
If you mean a valve which looks similar to the on in the photo below, you have a fully pumped system, not a gravity one.
There are three possible causes for your problem:
1. The 425 Tiara has been set to Gravity
You can check this by the action of the CH and HW slide switches. If they cannot be moved completely independently, the system is set to gravity.
You change this as follows:
Selecting Twice on the HW selector slide, then select Off on the CH selector slide, this will reveal the screwdriver slot in the interlock. Position a screwdriver in the slot and rotate clockwise (a stop will prevent the interlock from being turned too far).
If this solves the problem there is no need to check anything else.
But if not,
2 Incorrect wiring
Check that there is a wire connected to terminal 3 (HW OFF) on the 425 Tiara.
Check that there are wires connected to all three terminals of the thermostat on the side of the cylinder.
If this is wrong, let us know for further advice/instructions.
But if OK,
Faulty valve actuator (the box on the top).
Do you have a multimeter? It will make fault finding easier on the valve.
The valve has four wire (plus earth): white, grey, orange and blue.
Check the voltage between blue and each of the other three wires when the system is just calling for heating. They should all measure 240Vac. If white and grey are OK, but the orange measures 0Vac or something else, the valve actuator is faulty. Depending on valve make and model, you may be able to buy the actuator on its own.
Thx for the info the stat on the side does have 3 wires and im pretty sure its a gravity system as the water comes from the tank in the loft below is a pic just to help to confirm also the pic is with the old timer on so discard that. I dont have a multi meter but will have to get one, but have changed the setting on the tiara to fully pumped anyway just to see if that works.
You are getting confused over the use of the word gravity, when it's used in hot water systems. Yes, the water is fed out of the hot tap by the pressure of the water in the cold water tank in the loft. But "gravity" is also used to describe the way the water in the cylinder is heated. In this case "gravity" mean that the cylinder is heated by natural circulation, i.e the hot water leaving the boiler rises to the cylinder because hot water has a lower density and falls back to the boiler because its density increases when the heat is transferred to the water in the cylinder.
But you do not have this type of system; yours is fully pumped. The evidence for this is the three port valve in the picture. Water leaves the Grundfos pump and enters the valve. It can then go to the cylinder (left pipe), the radiators (right pipe) or, if set to mid position, to both left and right pipes.
If the timer was set to gravity, it would explain your problems. But any half-decent plumber should have found that.
Hint: There is no need to "quote" a complete post when you reply, just use the "Postreply" button at the bottom of the page.
Right now I get you sorry for the confusion.
I set it to fully pumped and it still shuts of once water is heated.
I set it to fully pumped and it still shuts of once water is heated.
Now check the other two possibilities I gave (faulty wiring and faulty actuator).
will get a multi meter tomorrow and let you know the out come.
Right I just checked the wires on the tiara and there is a wire connected to the 3rd terminal see pic below also don't have a multimeter yet am looking at this one http://www.screwfix.com/prods/34028...ols/Circuit-Testers/Pocket-Digital-Multimeter will it do the job?
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