Burner Questions

C

Chris Tharpe

New member
The burner currently stays running for a bit after the machine is set into bypass. Pressure switch seems to be working correctly and there is a GP thermostat on the machine as well. Any ideas on where to start.
 
Big Mike said:
Check the entire system for water leaks. If that's OK, then I'd look at the flow switch.
Click to expand...



no flow switch in the system its a pressure switch. The burner stays on longer the hotter you turn the thermostat up so I am feeling its related to the thermostat. I will try to take the thermostat out of line this evening and see what happens. If its still doing the same then i eliminated that part and its either a sticking fuel solenoid or pressure switch right?
 
Yes. Pressure/flow switch is the same thing (in theory). It controls the seleniod on the burner. I doubt it's the thermostat, because it doesn't control the flow of fuel to the burner, just the temp. Hopefully some more folks will chime in with suggestions.

This could be a potentially dangerous problem, because if the burner continues to run with the pump in bypass, the water in the coil is being super-heated and could lead to a nasty coil explosion. Make sure you get this repaired before using the rig for any work.
 
Big Mike said:
Yes. Pressure/flow switch is the same thing (in theory). It controls the seleniod on the burner. I doubt it's the thermostat, because it doesn't control the flow of fuel to the burner, just the temp. Hopefully some more folks will chime in with suggestions.

This could be a potentially dangerous problem, because if the burner continues to run with the pump in bypass, the water in the coil is being super-heated and could lead to a nasty coil explosion. Make sure you get this repaired before using the rig for any work.
Click to expand...

Russ Spence said:
could be a unloader, we had one doing the same thing and the valve in the unloader some how had the oring it sits under turn sideways and get into the valve spring and the burner would continue to run
Click to expand...

Russ is probably real close to the truth here. just because you close the gun, doesn't mean the unloader is doing it's job. If the pressure doesn't zero out immediately, the pressure switch thinks you're still working. Run the machine and listen for it to actually "unload". If the machine sounds the same whether the trigger is pulled or not, it's bypassing under pressure and not actually unloading. Usually a bad o ring on the outlet piston is at fault, sometimes the piston will just get stuck. Take the fitting out of your unloader that attaches to the connector hose going to the coil. The piston is in there.
 
Turns out there was a busted spring in the pressure switch that was the culprit. Funny tho because after a minute or so in bypass the burner would kick off.
 
nice find can't see thru metal,
 
Good to see you posting John!
 
When a burner stays on it is usually a pressure switch. Anytime that happens that spring is usually the first thing I check, I have seen that a lot over the years and it is a pretty quick check.
 
Flow Switches... are MUCH better than pressure switches... <O:p</O:p
We want the heater to go on ONLY when there is FLOW, not just "trapped pressure."<O:p</O:p
I like the ST5 Flow switches best for up to 4000 psi, especially because they are easiest to troubleshoot, and they last for many years.
note: the new TMT flow switch is a device which is a little more difficult to troubleshoot,
as a magnet doesn't affect it, and when they fail, they fail in the on position more often than off.
Another real important thing to know about pressure and flow switches...
they should NEVER be used to turn on a Hi Voltage igniter...<O:p</O:p
The inductive reactance in start-up of the HV draws BIG current, like starting a motor...
WAY too many machines are "eating" HV igniters on 12vDC.
..and coincidentally pressure switches, and those adjustable temperature controls.
They require a power relay... An automotive style 40 amp relay will last about 12 to 24 months.<O:p</O:p
The 70 amp version will last 4 to 7 years. You can expect 4 to 5 years of use on a HV igniter. <O:p</O:p
We proved this, when we did the initial field testing for Beckett before they released them out in the industry... in the early 90's.
We wrote the schematic in their Owners' manual that shows the 70 amp control relay,
..and have proven this to be the Longest-Term, Lowest Cost.
For you guys that stick with the pressure switch..
..Also plan on replacing your heater coil every 6 to 7 years,
as the heater blows easily from the combination of pressure-switch controlled heat without redundant safeties (like we use on ALL our hot systems).
Did you know your system is only half protected by a pressure-relief on only ONE side of a pressure-actuated unloader valve ??
..That's another reason to prefer a flow-actuated unloader valve.
There is SO much to know about these systems ! .. you NEED a good tech !
be CAREFUL buying used equipment,
and NEVER "guess at" how to fix or build your own.

If you'd like info on how to upgrade a system to last, e-mail, or call me.
we are a manufacturer WITH a full service center,
so we are famiuliar woth our competitors' failures.
 
one more thing..
Don't bother to rebuild a pressure switch..
by the time one side fails, the other is soon to follow.
and remember..
You specialize in cleaning contracts, NOT crash-course electromechanics.

:slap:
 
elimination of weakness

the truest path to strength..

is the elimination of weakness.

Never forget this.

Especially if you understand the elimination of "self-perpetuating mistakes."

:dance:
 
What I used to have happen alot with flow switches is they would freeze in cold weather because someone would not drain the machine (ME) then after they would thaw out they wouldn't work anymore.. Chris I think I have an extra flow switch in my toolbox if you get in a bind.. I can show you how to hook it up..
 
I will go through my stock of pressure switches (4 left) then move everything over to flow switches. I hear flow switches are a pain to deal with is why we have not changed over to them
 
Flow switches do have a weakness.. 3 amps max load !
they must be wired in a conrtol circuit to turn on no more than a fuel solenoid,
or control relay.. then you get reliability.
e-mail me for helpful wiring diagrams.

About the freezing thing..
it's a sunny 72 degrees today..
SanDiego is a nice place to visit, and easy to work in.
:dance:
 
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