Upgrade to direct vent / sealed combustion oil boiler

jmbw

I recently moved to a new place and I'm interested in upgrading its oil boiler (a ~15yo Weil-McLain WTGO-5) to a direct-vent unit, since I gather everyone hates power vents and draft inducers. It's not terrible, but you can absolutely smell the exhaust in the house from this one, which isn't surprising since it shares a flue with a backup Tarm wood boiler (no longer legal and was never a good idea, even though we never run both at once). So I'd love to leave that chimney to the Tarm contraption and vent the regular boiler through a wall. There's a perfect one within 10' of the boiler (basement wall is exposed on the outside and not near any windows).

I've tried obvious things to fix the current setup: the chimney was recently cleaned, the boiler had its annual service, I rigged a cat door with hardware cloth over it to let outdoor air (but not squirrels) into the boiler room, and I very slightly filed the ears on the barometric draft control so it would pivot correctly (it was just a teeny bit high of centered in the opening and kept getting jammed closed). So I think there's about as much natural draft as there's going to be, but enough exhaust is still leaking into the boiler room that you can smell it upstairs a bit. It's not enough to set off the CO detector, but it gives my girlfriend headaches. So I'd like to give up on gently persuading the chimney to accept exhaust it obviously doesn't want.

Aside: if it's at all possible, I'd love to do as much DIY as legally possible here in Massachusetts (which I realize may be "none"). At a previous house I replaced a gas boiler with a condensing hot-air furnace 95% myself (bringing in a pro at the very end to check my work and adjust everything) and it worked out *great*. Eventually. (Good thing Goodman had a good warranty -- at least the SECOND blower and control board were reliable.) THAT round of headaches totally cleared up (it WAS setting off the CO detector) and the house was finally warm enough. So I'm full of foolish confidence. This looks like a much bigger project but I'm no stranger to soldering (including plenty of plumbing repairs to the WTGO at another previous house, thanks to acidic well water) and at least I wouldn't get cut to ribbons by all the !@*^% sheet metal work! I'd gladly trade weeks of waving a torch around to avoid repeating that. It sucked hard.

BUT ANYWAY, separately from whether DIY is allowed or advisable, are DV oil boilers even really obtainable? Googling around, I see that the Weil-McLain UO "Ultimate Oil" boiler might be just what I want, and staying with WM would be OK with me -- with my previous WTGO, the QB-180 burner was the constant PITA but the boiler itself was rock-solid for 20 years, and this one (with a Beckett burner) has been great so far. The Peerless WB90 looks like another good candidate. But is either one still being made? The manufacturers' web sites make them sound like current products, but no one I can find has either one in stock (except a surplus place on eBay that has a few NOS UO-5s of unspecified age with no warranty) and a few supplier web sites specifically call them "discontinued", although I realize resellers can be a little careless with that word when they lose interest in a product.

Finally: how do I tell what size I need? I'm assuming UO-5 or WB90-04 since their specs are the closest to my WTGO-5, which heats the house just fine as long as you pour enough oil into it. (This place is really drafty -- next project!) But for reasons I don't understand, the WTGO-5 is not involved in my domestic hot water. The tankless coil is left unconnected (so why didn't they just use a WGO-5?) and there's a ~60 gal electric water heater which *is* connected to the Tarm wood boiler through a pump and an elaborate system of shutoff valves (currently set to disable all that and leave the Tarm out of it) as a storage tank.

My previous house had a WTGO connected in parallel with a 30-gallon Bock booster tank and even though heating hot water with other hot water sounds nuts to me, it worked *great* (100% reliable and I've already had to replace a heating element in the electric one at the new house) and I'd much rather put something like that in here than continue paying for electric hot water. But that's going to eat a bunch of MBH out of the next boiler's capacity. Where/what do I measure to figure out whether a UO-5 or WB90-04 can spare it? (There's no bigger size! And if my WTGO-5 is already at its limit, then I'm out of luck, unless I want to go down a twin-boiler rabbit hole.)

Thanks / John

Steamhead

I bet your odors are coming from the boiler, not the chimney. Before you spend all that money, get a pro to look it over- where in MA are you located?

jmbw

Royalston. It's near ... nah scratch that, it's not near anything. I'd *love* it if the current boiler were fixable! The guy (from Robillard) who did the annual service seemed sharp but even I can sometimes seem sharp so maybe he did miss something.

Steamhead

Try @Charlie from wmass . Not sure he goes that far, but if not, he might know someone who does.

jmbw

Thanks -- I sent him a msg. Royalston is kind of a haul from Springfield but it never hurts to ask. While I was typing I remembered a detail: we did ask the annual-cleaning tech about the smell, and he thought we were just smelling the glycol (the boiler has a loop going to a rarely-used Modine heater in the garage -- I *hope* that's the only reason someone added antifreeze). That's insane, right? I've boiled over my car enough times to recognize the smell, unless the stuff used in boilers is different enough to smell like truck exhaust instead of artificial maple flavoring.

Any guesses for what would make the smell other than poor draft? The tech said the boiler looked to be in decent shape for its age, which I hope means no giant cracks or anything.

Thanks!

EBEBRATT-Ed

I would call a certified chimney sweep. Have him look at the chimney and see if it is capable of providing enough draft for both units although wood & oil in the same chimney may not be a good idea.

Has anyone doing the "cleaning" ever taken the smoke hood under the jacket off the boiler and cleaned the boiler properly?

I would suspect not because most are too lazy.

I would also do a heat loss of the house using the Slant Fin app you can do that yourself.

You should do this in event you change the boiler someday anyhow.

IF it was me being cheap I wouldn't toss a perfectly good boiler without trying a bunch of things.

Is there a damper in the wood boiler flue you can close when you are not burning wood to help the Weil Mclain?

And your "technician " might down fire the Weil Mclain 1 nozzle size, chances are you have more input than you need and he could do a combustion test and check the draft.

And that's another reason for doing a heat loss, to see if you can downfire the boiler

HVACNUT

If everything is running fine, the 1998 and newer GO boilers are extremely easy to clean. The earlier revisions were pretty tight between the sections. 
Were you left with a printed copy of the combustion test? That's the first thing to check.
It "shares" a flue with a wood boiler. Maybe that's the first thing to check. No backdraft down through that flue?
Download the free Slant/Fin heat loss calculation app and do it yourself. You'll probably find your 5 section is 2 sections too many.
I've worked on a few WM Ultra Oil with the Beckett NX. They seem to run fine when set up correctly. 
You can downfire an EK Frontier and direct vent it. But EK isn't for DIYers.

kcopp

Direct vent boilers are a real challenge to get right.
If they are set set up perfect and the vent pressure not perfect they can give you nightmares. Furthermore when it gets really cold out the incoming air will change the way the oil is atomized flowing out of the nozzle. You can set the boiler up when its 40F out and it will be fine....at 10F not so much.
Figure out the chimney. It may need a liner.

Ctoilman

I second that about nasty performance with direct vent. Really havent seen a DV boiler run clean yet.  Most have all sorts of issues just to run.  You shouldn't have any smells with a chimney vent.  Nada.

jmbw

OK you guys make a good case for trying harder with the existing boiler. So I will. Thanks!

I moved in in August so the boiler's only been serviced once, and because of COVID I didn't hover asking dumb questions like I usually do. So I don't know what the guy did other than it took longer than I'm used to -- he said he likes to be thorough the first time with a new customer so he knows the system next time. Cheaper than I'm used to so I don't think he was padding the bill, but again I didn't watch. The only detail I remember was that he had to drill (and later tape) a hole in the vent pipe coming out of the boiler, for a probe, because apparently no one had ever done it before. If that tells you anything.

I don't remember getting a combustion test printout, but if I think hard enough I don't remember *not* getting one either. I'm highly suggestible. I'll root around in this mess and see what I can find.

Damper on the Tarm -- hmm yes there is one but someone's put safety wire through the handle so it's open all the time. Well that's ridiculously easy to change, so I'll do that right now and see what happens.

Thank you everyone!

EdTheHeaterMan

That smell may be the result of the start-up of a lean fire. With too much air blowing trying to blow the flame out before it even gets a chance to start, there will be a little extra fuel to ignite causing a small puff. that puff may not be enough to make a loud noise but it is enough to build up enough pressure on start-up to make some of the exhaust gasses find their way out of the exhaust pipe seams, the boiler door gaskets, and the barometric draft control (if equipped with one). Once the lean fire is established, the draft will then draw the exhaust gasses up a properly working chimney.

That smell may be a result of a partially plugged chimney.

If you do decide to go with a direct vent, The exit point of the exhaust pipe will have some odors that may be offensive from time to time. My oil burner was sidewall vented and with certain weather conditions I was able to smell the exhaust (usually days with no wind or very low wind) ... so select your exhaust location carefully.

Also, keep the venting instructions near the burner. I had a local fire inspector tell a customer that the insulated venting material provided by the manufacturer was not a proper venting material for the appliance He assumed the insulated venting material (flexible SS inner liner/insulation/aluminum exterior) was not appropriate because he believed the exterior aluminum covering was just a piece of dryer vent. This happened 5 years after the installation was approved by the same inspector. The customer called me about this problem and I charged them a service visit to see what the problem was. I then called the inspector for clarification and he said the aluminum dryer vent is not acceptable for venting.

The customer did not have the installation instructions available so I needed to get a copy off the interweb and send it to the inspector. If the customer had the instructions there, the problem may never have happened. Also if the customer purchased a service agreement from me and had the system maintained, I probably would not have charged them.

BTW it was a Becket NX burner and I set it up properly with instruments and guess what. It was clean as a whistle in the HX. After that, the customer purchased a maintenance agreement to handle the oil filter, nozzle changes, and air filter replacement, along with the rest of a complete maintenance visit.

jmbw

Interesting. I don't know what's normal, but the burner on this WTGO-5 runs (purposely, the guy who cleaned it said) for a few seconds before it even *tries* to ignite, and also after the burn is complete. With the QB-180 on my old WTGO-3, if it's spinning, it's trying to make fire, so any delay in the FOOMP means it's time to clean or replace the electrodes YET AGAIN. So does this burner's habit of building up a stiff breeze before turning on the oil/spark flow maybe explain it, if the boiler's running lean?

Also, is that bad? It is in a car, but this talk of down-firing makes it sound like oil boilers give you some leeway to dial up different amounts of flame w/o regrets. At my old house, annual cleanings seemed to almost always involve changing the nozzle size, either up or down, alternating every year. EVERYONE thought it was set wrong! It was pretty funny. No noticeable difference in behavior either way.

EBEBRATT-Ed

@jmbw
The more modern burner controls have pre putge and post purge. If you have one of those it COULD be perfectly normal for the burner motor to run with no flame on start up and shut down fro a few seconds. That will help the draft get going

STEVEusaPA

Your QB180 most likely has an oil valve on it, but it's not necessarily or always a delay oil valve. The longer it runs and the hotter it gets, the less likely it actually delays. It could also be simply a vacuum leak, or weak ignition/bad ignition wires, or as mentioned earlier, too much air and/or draft. But it's usually not too much overfire draft with a WM Gold.
As far as constant nozzle changing, that's just unprofessional guessing. These burners dial it pretty well with a clean heat exchanger, and set properly with combustion equipment.