Lochinvar WHN combustion analysis

Steve Minnich

Let me start by saying I love this boiler. Everything about it is top shelf! Except for two minor, but important, details.

In order to perform a combustion analysis, you have to remove the flue gas sensor with a wrench in places an arm can barely reach, let alone a wrench and the wrench has a swing radius of about 3/16". On the KBN's, the flue sensor is on the outside of the boiler and just pulls out. Easy stuff. I get it done on the WHN's but it would be so much easier to have a capped port for it, ideally at the top of the boiler with a vent fitting that doesn't have to be glued (the second thing I'd like to see changed). Maybe something similar to what Buderus used (uses) on the GB142's?

I'll probably just go to the standard of drilling a 1/4" hole in the flue, tapping it, and plugging it when I'm done with a stainless steel tapered plug and a bead of high temp. silicone or the like on the threads.

Anyone else find this unnecessarily difficult or are my fingers just too fat?

Did I mention I love this boiler?

hot_rod

Max keeps a very short, metric open end to loosen that. It's plastic and usually comes out by hand once you get it loose.

If you were to vent with Centrotherm, they have a starter piece with a capped port. Sort of like the port on the TT.

Steve Minnich

Thanks HR. Good to know. I'll have to get a shorty myself. I also picked up a length of 1/4" hose to bleed the vent up at the top of the boiler. I've been venting with CPVC this past year.

Steve Minnich

Help? On the left hand side is the flue gas sensor on the WHN. Would anyone happen to know what size metric wrench is need for the flats on the black plastic fitting?

hot_rod

looks like about a 12mm. Buy a whole set of double end, open ends metric wrenches at HD for 10 bucks or so. When you have the correct one, cut it down to about 4".

Steve Minnich

Thank you, Hot Rod.

JStar

Do yourself a favor and buy a few hundred of these 1/8" stainless steel plugs. After drilling the (C)PVC, the plug will self-thread into the hole and seal up nicely.

Dobber

I to am a fan of the WHN. love the control strategy. Especially the anti cycling feature for small loads. I couldn't agree more with the frustration of doing a combustion test. Every mod con out there has a port and some even on the combustion air side.
One other pet peeve ,minor, is I wish one of the heat demand contacts had priority so that if you have a small high temp load you could set it for priority and the pump/ ZV that is serving your low temp would shut down therefore saving the cost of a mixing station and increasing the efficiency of the overall system. I currently do the same thing with a switching relay but would be easier if it was built in to the controls.

Steve Minnich

I've drilled, tapped, and plugged the last couple I've done. The single biggest thing I'd love to see changed is getting rid of the glued vent fitting on top of the boiler. There are better ways.