Weil Mclain 299 Evergreen gas boiler

Johnnyfly41

Trying to get this new boiler working... A couple of struggles,,, Still chasing air out of my system so getting occasional Low water cut off signal locking out the boiler... Simple installation using input 2 for the heat call... All my circulation pumps in my system are turned on by the thermostat, my boiler is only powerin the system recirculation pump. Besides the LWC happening, the boiler fires up, does a pre purge,, lights off, begins heating,, then it stops, does a post purge and it keeps cycling in this way... Trying to understand, is this normal operation ? It's never really getting up to max temp... But, could that be because the outside air temp at the time was 59 degrees ? I need some guidance on troubleshooting this,, Is it a setting I do not have right ? No other faults... other than the LWC open fault when that happens....

pedmec

are there any error codes?

HVACNUT

This is DIY?
Natural or LP gas?
Pics? Is the piping correct according to the manual?
Is the primary loop purged?
Is the secondary loop purged?
Is ODR even connected?
You don't say what temperature the boiler reaches when it shuts down. It should say right in the display. 
The boiler circulator (recirculation pump is wired to P8?
Who's checking gas pressures and making necessary adjustments while doing the combustion test?

Johnnyfly41

Yes, it's wired correctly, circulation pump is running. And was professionally installed but my contractor is pretty buried right now so trying to do what I can to trouble shoot it... I have purged and purged the circuits, but, it seems there is still air in there... When it heats, I can hear gurgling in the boiler chamber, that tells me air is in there... The LWCO switch will just open momentarily. That sends it in to lock out.. .Hence why I am seeing the pre purge post purge..... I am using the Wiel Mclaine pre made circulator manifold and everything seems to be working normally. Just fighting this air thing I guess.... I was thinking if there is air in the top of the boiler chamber or recirculation loop, maybe with everything shut off, I could unscrew the LWCO switch until it leaks and see if I could bleed the air off there. My large air trap, I vent that, it only ever has just a tiny bit of air. Large ranch home, boiler is in the basement at the lowest point. This is a natural gas boiler... Pretty sure gas pressure is not the problem, previous old boiler was 450,000 BTU and it was fine with the gas pressure. We will need to check that and adjust the gas valve for proper flame, waiting on my guy to bring CO2 probe to do that.... No error codes are flashing, except when the LWCO switch trips it out..... Thank you for all the replies,, back to pushing water through it again today.....

dko

~

Johnnyfly41

I don't know what ODR is... I have the two system temperature sensors connected, readings are working.. The external sensor on the boiler output, matches what I see on the pressure temperature manual gage on the recirculation manifold. Outside air temp is connected,, Using Input 2 for the heat call, Most of my radiators are finned, but, I have two zones that are in floor heat, which are fed through mixing valves of course... So it seemed to be best to use input 2 in the default for finned radiators.. Temp rise depends on how long before the LWCO trips it, but, that seems normal I have seen like 130 before it trips out... I think boiler is happy with all connections.. Nice clean short runs for the intake and exhaust, done per the manual, only sweep angled pieces,
they are away from each other outside... No system faults other than the LWCO. My old boiler was an old cast iron unit, a dumb boiler.... I would purge the system every year pushing water through it but, no LWCO in that unit... So this very sensitive system is kind of new to me.... My home has 5 zones, all on one level, ranch home.

hot_rod

Whats the pressure in the system?

sometimes pop open the relief valve to get trapped air out of the top of the boiler

The air pockets could trigger the LWC

Johnnyfly41

Thanks hot rod, thats excellent advice,,, I did that yesterday accidentally as I was purging... adding water manually as I was flushing the system and I popped it... Update... I purged all 5 zones, 8 circuits because one is split up.... 3 did indeed have air in them still !!! Started boiler, no LWCO tripping and it's been running for some time now.... Question... My upper limit for water temp is 180... The boiler right now went to a target temp of 145 and is holding there... Is that a function of the Outdoor Air Temperature ? As in, warmer outdoors, it modulates the water temp down ? My OAT sensor seems to be reading 12-14 degrees higher than the actual temp... My exit point for that and the direct venting is a plywood panel installed in a basement window... Exits to a very large window well... I attached the OAT to the plywood and I think that is why it's reading higher than ambient... If that is going to affect performance, I think I am going to put some spacers behind it so it has outside air all around it..... Thank you all for your most excellent advice and assistance.. Very much appreciated !!!! John

heathead

My exit point for that and the direct venting is a plywood panel installed in a basement window... Exits to a very large window well... I attached the OAT to the plywood and I think that is why it's reading higher than ambient... If that is going to affect performance, I think I am going to put some spacers behind it so it has outside air all around it.....

Sorry don't know how to highlight this from your post. The exhaust is going into a window well with plywood covering the window doesn't sound great at all. Can you post some pictures of that. You may kill this boiler in a very short time. Is the intake from that area also??

Johnnyfly41

The air intake is within the window well with a critter grid over it... The Exhaust goes up and well out of the window well.. Not near each other at all.. It was my only way to get them out of my house.

KC_Jones

Johnnyfly41 said:

The air intake is within the window well with a critter grid over it... The Exhaust goes up and well out of the window well.. Not near each other at all.. It was my only way to get them out of my house.

Do you get snow where you live? If so that arrangement will be a problem based on your description. Also double check your manual, there are usually specific requirement for the intake and exhaust location and proximity to one another.

By your description I'd guess the temperature sensor issue is due to the combustion gases altering the localize temperature of that area.

Look in the manual, there is a specific location that temperature sensor is to be located. It's usually a north/north-east face in a shady spot so that it isn't influenced by the sun. Also, located away from the boiler exhaust, again so that warm exhaust doesn't impact the temperature reading.

Johnnyfly41

I did look at that and the exhaust is at least three feet above both the intake and the sensor.. The window well is under a 3' deep overhang and is quite deep and shaded by large pines on the east side of my home.. No sunlight can ever hit it and the window wells never fill up with snow... I have way more separation on all these things than the manual prescribes... I would like to understand what the boiler does with OAT information.. I know it will cut off the boiler if the OAT gets to 70. It's looking like it also varies it's target water temperature based upon the OAT... Because as I have been messing with the boiler, I have seen that it's target temperature has been different at different times.... The only thing I can think of is that it is deciding that based upon the OAT.

j