Another Ultrastore Problem

[farmerbob]

Hi
Got the ultrastore working fine eventually. Left the caravan un inhabited for a few weeks, just got back to it and now the water heats up to temperature on gas nicely. Once at temp the burner switches off as the thermostat recognises the temperature. Then the red light of doom clicks in, rather than staying green as it would normally. If you then run the hot water out until it becomes cold again I would expect the gas to relight by turning the ultrastore off and on again but it just goes to red light light and will not do anything else for about 15 minutes. After this time if the ultrastore is turned on the gas will ignite and it will heat the water again. What has failed. Is the over-temperature sensor (yellow wires ) faulty? Can I check the resistance is within tolerance?
Thanks
James

 

[ProfJohnL]

The red light indicates the appliance has tried to light the gas but it was unable to detect a proper flame, and after about 10 seconds it "lock out" and displays the red LED.

The fact the heater lights from cold, proves the the gas is getting through and able to light correctly. But the display of the red LED suggests the heater may actually be over heating and the controller is closing the gas valve, causing the flame to go out and the controller to then go to lock out.

This reads as though its a water temperature control has failed. My suspicion falls on the main PCB, as its unlikely to be the temperature sensor itself.

I would urge you not to attempt to repair the PCB, as its is a critical part of the heaters safety system.

 

[farmerbob]

Thanks for your reply. I had the PCB checked just recently with a previous problem, it was reutrned as working well.

Do the over-temp and temp sensors have a good realiability reputation?

Is it possible to check the operation resistence of the sensors?

 

[tanis8472]

Have you removed the cover on the outside?

 

[ProfJohnL]

Have you removed the cover on the outside?

I suspect the OP has already resolved his question as its virtually a month since the last post.

 

[tanis8472]

Be nice to know the outcome 🙂

 

[tanis8472]

I found out that it will not stay lit with cover on. Not surprised really as it would probably melt it and cause back pressure.

 

[ProfJohnL]

I found out that it will not stay lit with cover on. Not surprised really as it would probably melt it and cause back pressure.

That sounds as though you have experienced it!
A trumastore that is fully functional should not be able to cause the outer grill cover to melt if its been left left on. The way the burner is set up in the heater , there is a burner which almost is a complete ring. When gas is applied a spark igniter will try to ignite the flame at the beginning of the burner, the flame front should progress around the burner in less than a second, and at the end is a flame detection electrode. When a good flame meets the electrode, it connects teh elctrod to the metal burner bar and signals to the control circuit the flame has been established which stops the ignitor and cancels the lock out timer. All good

Anything that either prevents the flame from reaching the end of the burner or corrupts the flame such that its not big enough to touch the electrode, or possibly being disturbed so the flame lifts off the burner, will tell the control to turn on the ignitor and restart the time out counter. If the time out counter reaches its limit it shuts the whole gas side of the heater down, and displays the red warning LED on the wall switch.

If the external cowl cover has not been removed, it firstly restricts some of air the heater needs to burn the gas and the exhaust, so like a school bunsen burner with air restricted the flame becomes languid and tends to yellow, This type of flame does not spread around the burner so easily and also has tendency to lift off the burner breaking the flame signal to the controller. It uses up the air faster than it can be replenished though the cowl and the flame will quickly stifle and go out causing the controller to lock out to red.

For a trumastore burner to be able to produce enough flame and heat to melt the out cover would need several other factors to be awry, suggesting the gas sytem or heater may not have been correctly maintained.

 

[RogerL]

That sounds as though you have experienced it!
A trumastore that is fully functional should not be able to cause the outer grill cover to melt if its been left left on. The way the burner is set up in the heater , there is a burner which almost is a complete ring. When gas is applied a spark igniter will try to ignite the flame at the beginning of the burner, the flame front should progress around the burner in less than a second, and at the end is a flame detection electrode. When a good flame meets the electrode, it connects teh elctrod to the metal burner bar and signals to the control circuit the flame has been established which stops the ignitor and cancels the lock out timer. All good

Anything that either prevents the flame from reaching the end of the burner or corrupts the flame such that its not big enough to touch the electrode, or possibly being disturbed so the flame lifts off the burner, will tell the control to turn on the ignitor and restart the time out counter. If the time out counter reaches its limit it shuts the whole gas side of the heater down, and displays the red warning LED on the wall switch.

If the external cowl cover has not been removed, it firstly restricts some of air the heater needs to burn the gas and the exhaust, so like a school bunsen burner with air restricted the flame becomes languid and tends to yellow, This type of flame does not spread around the burner so easily and also has tendency to lift off the burner breaking the flame signal to the controller. It uses up the air faster than it can be replenished though the cowl and the flame will quickly stifle and go out causing the controller to lock out to red.

For a trumastore burner to be able to produce enough flame and heat to melt the out cover would need several other factors to be awry, suggesting the gas sytem or heater may not have been correctly maintained.

From experience, it won't stay lit if the cover's on - got the T-shirt!

 

[Mel]

I found out that it will not stay lit with cover on. Not surprised really as it would probably melt it and cause back pressure.

Some years ago I was sitting on a pitch minding my own business. There was a sudden loud THWUMP and the external cover for the next door’s caravan shot up in the air and landed at my feet. At least it missed my head. The guy cam out and said “ the gas heater’s not working”. I returned said cover and said, it may well work better if you leave this off.
Mel