WM97+ No High fire or modulation

Grallert

Hi all We have a green house that's heated with a Wiel McClain 97+ It's cold and windy here in the Berkshires and the boiler should be making high fire. It's got a target of 190 but a supply of about 100. No errors. It's bouncing on and off with a firing time of well under a minute. Anything I should be looking for? It's running 1 1/4 fin tube perimeter single zone with dom water. Thank you for any insight.

EdTheHeaterMan

Either the parameters are not set correctly or the parameters are set correctly and all you need is 100°F water to heat the structure.

To further help you we need to know more.

Are you experiencing insufficient heat in the space or insufficient hot water?
What is the outdoor temperature?
What is the indoor desired temperature?
What is the indoor actual temperature?

Have you called Weil Mclain or the installing contractor?

Grallert

Thanks for the quick reply Ed. Both the water and the heat are insufficient. The boil is unable to satisfy the indirect which would I think, demand the maximum water temp of 190 which is the target for both the heating loop and the domestic loop. It's not crazy cold, 34 degrees. crazy windy. Keep in mind this is a glass house so we're not expecting miracles. But it's acting differently and I would expect to see the target being reached. The TT is set to 55 if I recall and we're about 10 degrees shy of that. apparently this has been the case all weekend. Installer is long gone. Oh and the parameters appear to be correct but that I'll double check. Thanks again. M

EdTheHeaterMan

Then there is a sensor that is not registering correctly. You will need to get Weil McLain tech support or a local distributor or dealer that has some experience with these. If the Tech is not experienced then you may be paying for his time on the phone with tech support and that can get expensive.

I would try a local distributor (Plumbing Supply Co.) or wait on hold for Weil McLain tech support yourself. This boiler has too many menus to scroll thru to find the problem if not experienced.

Ironman

Either a sensor is not "seeing" the correct SWT or you're not getting good flow through the boiler.

Grallert

Here's an up date for the future me or anyone else interested. It turns out the flame signal was wrong causing the flame to drop out after a very short period of time. apparently the signal was not strong enough to allow high fire. So if I'm not mistaken the solution is a service which includes an ignition rod and flame sensor. There is a temporary work around which works if the pumps are set to high. This will hold until the service materials arrive. In case you're concerned this work around was recommended by the WM service line.

EBEBRATT-Ed

@Grallert
Sombody is telling you a story that's not true. Either the boiler is firing and staying on line but not providing enough heat or it's going on lockout and being reset.

The flame sensor has nothing to do with high fire.

If the burner won't stay running address that problem first.

If it won't go to high fire after the flame is established thats another issue.

Find the control that runs the mod motor for low high fire, Its probably a Honeywell L91A or B

once the boiler is firing on main flame pull the wire connected to the white w terminal off and see if it goes to high fire. Could e a bad mod motor, bad mod control or the wiring inbetween. Could also be a pad primary control which controls the switching to the mod control

Grallert

Interesting. Reprogrammed to a 110 as per wiel mcclain it's been running normally. The maintenance kit arrived yesterday afternoon so that's on my list today if the creek don't rise.