Gas conversion pointers please.

Chapstick

Hello everybody. This weekends project is a gas conversion for my Weil Mclaine SGO-3. All the parts are ordered and I have somebody coming by after the install with the computer to calibrate it for efficiency. My concern is the chimney. I have a guy coming by to clean/inspect it and from what I can tell, getting it re lined is a must. Can I run the converted boiler through the old flue for a week or two if these guys can't get it installed in time ?

Chapstick

And one more thing, the replacement burner calls for 7" flue piping. Is it safe to assume that the new liner will also need to be 7" ? I would like to know just in case the chimney guys don't know. Thanks in advance.

EBEBRATT-Ed

Putting the liner in shouldn't take long . I would hold off on the conversion until the liner is in.

Check your boiler manual. From what I found Weil Mclain recommends a 6" dia X 15' chimney for that boiler. 7" would be fine as well

nicholas bonham-carter

Is this a steam, or hot water system?
It would be useful to know the BTU needs of any steam radiation, or the heat loss of a hot water system. This will enable your burner tech to dial it in accurately, so it won't be over-sized.--NBC

Chapstick

It's steam and off the top of my head I think it's 120k btu. Beckett put together a very informative video and manual so all of the info he's gonna need is in it.

Chapstick

Ebebrat, the Beckett gas burner calls for 7". Since they bothered to mention it I'm going to go with their recommendation.

nicholas bonham-carter

This is the time to calculate the EDR of your radiators, so you can reduce the firing rate of the burner down to the amount needed to just fill the rads with steam. This is so your oversized boiler does not shortcycle itself into an early grave.
Do a search here and I believe you will find a complete description, and maybe a video.
Many people here have problems with oversized boilers, and you are at a point where you can do something about it.—NBC

Chapstick

I did one a couple years ago and it was pretty close to what the boiler was rated at. But now that we're on the topic, I am having cycling issues from pressure. I bought the lost art of steam heating and repiped all of the returns because the previous owner destroyed the system. When I did the job I had to install a vaporstat and dial it in at 12oz. If it was an ounce higher condensate would shoot out of one of the return vents. As per the book after I did the math the measurement and pressure was right on. There's no way of raising the return piping so the "A" dimension cannot be changed. Any ideas on a way to correct the problem ?

adambnyc

I will second all of this. I did an oil to gas conversion when first moving into my house. I didn’t know anything about these systems. Plumber that I hired swapped equal size oil for NG boilers and piped it horribly!!! Surging, no heat on some rads, banging pipes.

After repiping my boiler, fixing the venting and moving to a dual stage gas valve to downfire the boiler, the system is running MUCH better but it’s still oversized! I still build more pressure than I should.

Proper sizing and an evaluation before by a steam pro would have saved me a lot of money. I could have had a smaller more efficient boiler. And for probably the same price or close, it would have been done right the first time.

Chapstick

What did you do about your chimney liner when you did the swap ?

Chapstick

Man, the chimney guy just left. Apparently there was never a liner installed and the chimney is completely clogged. It's pretty bad.

adambnyc

I didn’t need a liner. I changed before they were required. I get the chimney inspected every year and cleaned when needed

EBEBRATT-Ed

@Chapstick , good thing you had that checked before the conversion. We don't need any houses with Co in them

Chapstick

It's amazing that we didn't have any already. I had somebody check out the chimney a couple years ago and he did some repairs. At least that's what he said. I lost his number so I googled his name yesterday and found out he's been arrested 3 times for theft by deceit since he was last here. Turns out he didn't fix anything on the chimney and lied to me saying it wasn't bad. Thank god I lost his number. He would've been here again if I didn't !

Tim McElwain

Have you ever installed a conversion burner before? From what I can tell from your posting it is a Beckett gas Conversion Burner. As someone who has installed over 3,500 conversion burners this is not something that should be undertaken by non professionals who have no training on the proper way to install and set up.

Chapstick

Yes I'm installing it myself and I have a licensed hvac guy coming over to go over it and adjust the flame when I'm done. I also rebuild gas turbine fuel nozzles assemblies which are far more complex than this single burner. I'm not concerned.

Chapstick

Worked like a charm. Just need a new chimney liner and a little tweaking and I'm all set.

nicholas bonham-carter

That’s great, and thanks for the update.
What sort of tweaking is needed?—NBC

j a_2

Nice job, by taking an active roll in the install, you saved yourself from the goonies....Can you post up a picture? Are you in a high or low pressure gas area? You my as well and go ahead and line the chimney yourself, pretty straight fwd of a task...cap it and be done with it....

Chapstick

Once the chimney is squared away my hvac buddy is going to come by and adjust the new dual action damper and gas pressure to get the efficiency as high as possible. Can't do it yet because the draft is definitely going to change once the liner is replaced.

As far as doing the chimney myself, I'm not that courageous. My roof is a 12 on 12 and the chimney is a good 30 feet in the air. On top of that it's crazy cold and icy outside. I'll pay the extra $$$ for that one. I don't raise the white flag that often but I will in this case !

j a_2

Safe combustion parameters, then efficiency....Efficiency can be greatly helped by tightening up your house, insulating pipes,and maybe resizing the radiators to match room heat loss...Why not go all the way, since your gone this far...I totally understand the roof issue....Are you in a high or low pressure gas area?

Chapstick

My house sucks ! The old man that owned it before me hit the lottery and made an attempt at sealing the place up but he went with the cheapest windows available and there's drafts everywhere. Also around the baseboards there's a cold draft. The front door leaks bad too. 2nd and 3rd floors get way hotter than the 1st and since somebody replaced the steam throttling valves for ball valves I have no way of regulating the radiators. No pipe insulation either. Still lots of work to do but it is a cool house so it's worth it. The heating system has come a long way and if it wasn't for this forum and the lost art of steam heating I couldn't have done it.

Chapstick

I repiped the boiler, rebuilt all the steam traps, and repiped the returns. I had to add F&T traps to the ends of the mains and add the pipe to get back to the boiler. Whoever worked on this system clearly didnt have the right books and killed the system.
2 pipe steam sucks. Too much stuff can break. At this point I need to add a nice big radiator to the first floor, insulate the pipes, and get the right valves and I'll be done. The piping is in place already so there was a radiator and it was removed at some point.

nicholas bonham-carter

Two pipe steam systems are much more adjustable than one pipe, where the inlet valve cannot be closed without causing various problems. The ball valves could be changed for gate valves, the the stem mounted horizontal, which allows the condensate not to build up at the inlet and cause water hammer, if there is a pitch problem.
You could also look into the possibility of vacuum operation, and using the hi-lo-hi firing controls on your new burner, if it has that feature.—NBC

Chapstick

Definitely agreed that 2 pipe systems have way more adjustability but there's just too much stuff that can break down. If a trap fails closed it's easy to spot but if it fails open who's going to notice unless they have a full understanding of how their heating system works ? I'm thinking I might have a bad trap because I sat and drank beers watching the gauges last night for 3 hours and didn't build an ounce of pressure. It's a big house, it's really cold, and there's no pipe insulation so maybe not but that right there is why I prefer a single pipe system. I have a single pipe in my other house and it never has any issues.

Chapstick

But all of the radiators get screaming hot and I have read that a perfect steam system doesn't build pressure. Any thoughts on this ?

Jamie Hall

Chapstick said:

But all of the radiators get screaming hot and I have read that a perfect steam system doesn't build pressure. Any thoughts on this ?

You are fortunate -- the boiler is the right size for the system. Unless, of course, there's a whacking great leak somewhere - which I think you'd have noticed by now.

On the traps. There's a secret sauce to longevity: keep the pressure differential across them low -- which is what you are doing now. The ideal is to not have them have to operate at all, of course, which is why adjusting the valve on the radiator to feed just enough steam to keep the radiator happy is so useful. For myself, anyway, I'd much rather have to cope with the odd failed trap and be able to balance the system to the way I want it on any given day with the radiator valves than have to mess with juggling vents!