Underslung LPG and propex misfires

markbox

Free Member

Messages
11
Hi

I installed 25l lpg tank underneath with two stage regulator.

Between regulator and propex unit there is 5 meters pipe.

Every time when tank half emptied I get 2 or 3 propex attempts to ignite.

Looks like gas not getting in fast enough.
That was last winter.

For this season is getting worst yesterday on full lpg tank 7 attempts to ignite propex.

Any suggestion please?
 

ActiveCampers

Full Member

Messages
150
What is the error code on the propex?
It may be coincidence on the gas..... Does hob light instantly?
Ours used to play up and randomly refuse to fire up, but the actual reason was almost certainly down to Mr Spider in the exhaust and/or blocking the air flow sensor (which in mine was the mechanical type, not the newer electrical type). So if you have an oldish unit - perhaps it could be that.
 

horace

Full Member

Messages
26
Hi if it's ok on a full tank but not on half a tank ,sounds like pressure check working pressure at tank when it's on and then at unit should be the same +or - 1mbr oh what size pipe is installed
 

markbox

Free Member

Messages
11
What is the error code on the propex?
It may be coincidence on the gas..... Does hob light instantly?
Ours used to play up and randomly refuse to fire up, but the actual reason was almost certainly down to Mr Spider in the exhaust and/or blocking the air flow sensor (which in mine was the mechanical type, not the newer electrical type). So if you have an oldish unit - perhaps it could be that.

Getting 4 blinks. Brand new bought last year.
What interesting is once it fired up.
It will work all night on and off but when I leave off for more than 12 hours then problem begins.
 
Last edited:

markbox

Free Member

Messages
11
Hi if it's ok on a full tank but not on half a tank ,sounds like pressure check working pressure at tank when it's on and then at unit should be the same +or - 1mbr oh what size pipe is installed

Between regulator and propex 8mm
All appliances were brand new on first install.
And problems on half empty tank begins from day 1.
 

Exwindsurfer

Full Member

Messages
1,112
I fitted a 38ltr underslung tank over 7 years ago and only had one problem with the heater but a quick trip to the people at propex sorted think they only had it day and half one superb service.
 

ActiveCampers

Full Member

Messages
150
Getting 4 blinks. Brand new bought last year.
What interesting is once it fired up.
It will work all night on and off but when I leave off for more than 12 hours then problem begins.
DO you turn off any stop-cocks? If not, the tank will be providing gas to the appliance all the time - failure to relight will be a heater issue, not gas. (the fact it works constantly overnight negates flow/pressure as a fault). If you do turn off a valve, then its possible you have a leak between the valve and the appliance resulting in no gas in the pipe and heater not starting.
I think considering the gas/regulator as the source of the issue is a red herring....
So do advise how/if you use any gas taps
And please do advise hob works perfectly all the time
And if the hob/heater are t'd off a manifold or something, run the hob so you can see the flame, then start the heater. The hob flame should be consistent. If it lowers, or changes colour, then regulator/flow could be at fault
 

horace

Full Member

Messages
26
hi could be propex unit if working all night on half tank ,pressure ok ,rectification on the electrode or pcb failing .please check all electrical connections and voltage , pcb's dont like low voltage if going below 12 volts pcb will fail safe
 

markbox

Free Member

Messages
11
DO you turn off any stop-cocks? If not, the tank will be providing gas to the appliance all the time - failure to relight will be a heater issue, not gas. (the fact it works constantly overnight negates flow/pressure as a fault). If you do turn off a valve, then its possible you have a leak between the valve and the appliance resulting in no gas in the pipe and heater not starting.
I think considering the gas/regulator as the source of the issue is a red herring....
So do advise how/if you use any gas taps
And please do advise hob works perfectly all the time
And if the hob/heater are t'd off a manifold or something, run the hob so you can see the flame, then start the heater. The hob flame should be consistent. If it lowers, or changes colour, then regulator/flow could be at fault

I cant see any flames as I use lpg for propex only at the moment.
 

markbox

Free Member

Messages
11
hi could be propex unit if working all night on half tank ,pressure ok ,rectification on the electrode or pcb failing .please check all electrical connections and voltage , pcb's dont like low voltage if going below 12 volts pcb will fail safe

Sorry I mean, once it ignites for the first time then all night it works fine according to thermostat on cycle on and off
 

markbox

Free Member

Messages
11
I think found the problem. Regulator head facing downward.
I spoke to someone today who owns factory build campervan with exact same regulator facing downward and he got issue with the cooker that would take good while to ignite.

Now I have to go under and inspect everything : )
regulator.jpg
 

SOD IT

Full Member

Messages
18
Ok this is what I have found with my system. Which is, low pressure side which consists of a truma 4e combi and a hob. A manifold a truma regulator and a truma 12v shut off valve operated by a switch. The high pressure side, the tank is a "gas it" 30 ltr.
Now, and I hold my hand up to this, I can never remember to switch off the shut off valve what a ring morrow now. Why the first few times trying to light the boiler I got a bang and it lit. A bang, the guy in the unit next door said it sounded like I'd dropped an 8x5 sheet of wood. The next time it blew the top hat off the exhaust manifold (see pic) the next it blew the air intake pipe off the inside of the exhaust blew off. Steadily it's got to the point it will not work at all.
However, this is because gas liquid is getting beyond the regulator.
So when I'm stood there whistling away keeping the black button pressed the gas tank has inside it a mechanism similar to a ballcock valve in the old toilet cistern.liquid gas rises the float rises until finally it shuts off the flow into the tank at 80%full. At this point when I've neglected to turn off the isolating valve the liquid starts to fill up the low pressure side. Oh the hob works great but the boiler won't.
I hope this solves your full tank problem and had a giggle about my learning process.
Your half tank, well all I can say is try turning your gas off at the tank or manifold before travelling and filling liquid gas will get through to your heater.

20200128_115747.jpg
 
Last edited by a moderator:

markbox

Free Member

Messages
11
Ok this is what I have found with my system. Which is, low pressure side which consists of a truma 4e combi and a hob. A manifold a truma regulator and a truma 12v shut off valve operated by a switch. The high pressure side, the tank is a "gas it" 30 ltr.
Now, and I hold my hand up to this, I can never remember to switch off the shut off valve what a ring morrow now. Why the first few times trying to light the boiler I got a bang and it lit. A bang, the guy in the unit next door said it sounded like I'd dropped an 8x5 sheet of wood. The next time it blew the top hat off the exhaust manifold (see pic) the next it blew the air intake pipe off the inside of the exhaust blew off. Steadily it's got to the point it will not work at all.
However, this is because gas liquid is getting beyond the regulator.
So when I'm stood there whistling away keeping the black button pressed the gas tank has inside it a mechanism similar to a ballcock valve in the old toilet cistern.liquid gas rises the float rises until finally it shuts off the flow into the tank at 80%full. At this point when I've neglected to turn off the isolating valve the liquid starts to fill up the low pressure side. Oh the hob works great but the boiler won't.
I hope this solves your full tank problem and had a giggle about my learning process.
Your half tank, well all I can say is try turning your gas off at the tank or manifold before travelling and filling liquid gas will get through to your heater.
As far as I remember regulator have to be fitted above lpg tank so the liquid won't get in and they advise two stage regulator on all underslung installs.
 
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