Weil-Mclain GV series circulator question

[AKJM]

I have a GV-6 series 2 with the main and bypass circulator. Infrequently, especially in colder weather, the bypass circulator is on and moving hot water back to the return pipe. The main circulator on the return pipe is also on and hot. However, no hot water is moving in the outflow pipe to the zones and the visual temperature gauge on the outflow pipe is bottomed at about 70F. Zones are calling for heat but the boiler doesn't ignite. The situation may resolve after 30-45 minutes or if I cycle the power off. When things resolve, the both circulators come on, the boiler ignites, outflow and return pipes are both hot, and the visual temp gauge is showing the normal water temperature spread.

I'm not sure if the system is running properly or not? Any time I have had technicians look at the system, it is obvious they don't understand the GV models that have two circulators or they want to sell me a new boiler. Any ideas? Thanks

 

[Fitter30]

Take a few pics of boiler, pumps and piping.

 

[Sponsor]

 

[John Gayewski]

I do not understand your terminology. Are you saying you have a primary secondary pumping system and your boiler isn't firing?

The circulators just come one when a call for heat is transmitted. The boiler failing to fire sounds to be the problem.

I'm not sure what model to have if you provide a link i could look at it.

 

[AKJM]

Black pump is the main circulator and on the return line. Green pump is the bypass circulator tapp

ing the outflow to temper the water in the return line. Boiler will go into long periods where both circulators are running but it appears the hot outflow is circulating thru the bypass back to the return line. When this happens the outflow pipe extending from the boiler is cool to the touch and the visual temp drops. This can happen while there is a call for heat (1 red light) or while burner is on (4 red lights). Eventually the outflow temp will begin to raise back to normal after a few cycles.

 

[John Gayewski]

I think your saying that you think the flow is being misdirected but the boiler is firing now?

 

[John Gayewski]

 

[John Gayewski]

Edit.

I don't have time to read through your manual but it seems you have to figure out what's setting off your bypass circulator.

This sounds like a control issue which is an area where I have the least experience comma but if you look up the manual there are replacement parts including the main control. Maybe someone else can figure out a way to determine if it's the main control module.

 

[Fitter30]

What are your heat emitters and what water temp are you running? Gauge looks like its about 10 lbs. Bottom of boiler the the hightest point of the system. Below 130° the bypass pump turns on. Cast boilers don't like return water temp under 140° they condensate and can crack a boiler section.

 

[AKJM]

I think your saying that you think the flow is being misdirected but the boiler is firing now?

Yes, the outflow temp drops quite low when the main and bypass circulators come on when heat is called. The burner does fire normally but it takes a few cycles to bring outflow back up to normal.

 

[AKJM]

Edit.

I don't have time to read through your manual but it seems you have to figure out what's setting off your bypass circulator.

This sounds like a control issue which is an area where I have the least experience comma but if you look up the manual there are replacement parts including the main control. Maybe someone else can figure out a way to determine if it's the main control module.

I replaced the control about a year ago. I temporarily put the old control back in, but I get the same issue. It looks like my problem (per manual diagram and notes) is a faulty water control sensor (#27 in diagram). This was replaced two years ago but may now be faulty. That's the only other thing that I believe controls the bypass circulator.

 

[AKJM]

What are your heat emitters and what water temp are you running? Gauge looks like its about 10 lbs. Bottom of boiler the the hightest point of the system. Below 140° the bypass pump turns on. Cast boilers don't like return water temp under 140° they condensate and can crack a boiler section.

Boiler services about 100 feet of fin baseboard and a boiler-mate water heater. Outflow water temp is set at 195F and normally would drop to 165F. Pressure is 10-12 psi for a single level house.

 

[Fitter30]

Post 4 top pic where does that wire go? That green pump should only run under 130°.

 

[Fitter30]

That sensor is than the one strapped to the return line? If so check to if its tight to the pipe. Take another pix of the label with model number need the bar code left column lower to get a resistance to temp chart for sensor. Why are you running 195°? 100' 3/4" fin tube is about 66,000 btu's.Need more heat thats why for 195.° Boiler is way oversize unless im missing something even with a sidearm water heater. Your record low -27° f
. Boiler have glycol in system?

 

[Fitter30]

I do not understand your terminology. Are you saying you have a primary secondary pumping system and your boiler isn't firing?

The circulators just come one when a call for heat is transmitted. The boiler failing to fire sounds to be the problem.

I'm not sure what model to have if you provide a link i could look at it.

This boiler doesn't have primary secondary loops. Black pump is for the fin tube green pump is for boiler protection where if return water temp.drops below 130° it comes on just to protect the boiler from thermal shock. Never seen this factory piped and controlled.