Opinion on Nozzle Sizes and Type for Oversized WM

NTL1991

My boiler is a Weil-McLain SGO-4 which provided steam heat to my 3-family home. The radiators were replaced with baseboard, the boiler was converted to hot water, and is used to heat the first floor, and two new hot water boilers were installed for the other two floors.



The heat loss for my apartment is 30,000 BTU/hr. Piping is a series loop using 3/4" copper and O2 barrier PEX. The boiler is rated at 131,000 BTU with a 1.20 nozzle.



The last combustion test was in 2001. That is when the system was supplying steam to the whole house. The nozzle was a .75/80 degrees. Of course, if I knew about nozzle sizes back then, and how it was so small, I would've tried putting in a 1.20 as per factory specs and then worked on the uneven heating issues I was having, rather than just tearing out the whole system and starting fresh... You live and learn, I guess.



When the boiler was converted to hot water, a Delavan .85/80 degrees was installed. Is it advisable to down-fire this boiler even more? I do not have a tankless coil installed.



 I know the boiler is grossly oversized for the apartment, but is there anything I can do short of replacing it?



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icesailor

Nozzle size:

According to the combustion analysis, it's already fired at .75 GPH. The CO2 would be higher higher if it was a .85 but it would take some adjusting.

A Carlin EZ-1 or Riello would probably save some oil but that's what you have.

I doubt seriously if the boiler has ever been properly cleaned. You MUST open the front to really clean it.

EddieG

Wow!

That boiler only supplies your 30,000 BTU apartment? That's a big difference. You can only down fire so much. I would imagine it is short cycling terrible. Some controls would help. Such as a Beckett Aquasmart or an ODR control. There are some other things you could do, but a smaller efficient boiler is the real answer. If you invest to much in band aids, you could have got a new boiler. Could you re-pipe the boilers so that they were staged and all supplied the entire building based on demand with a ODR controller? Why so many boilers? Is there separate oil tanks? Separate utility bills? 

Charlie from wmass

Weil tech told me the most they want you to down fire

is 1/2 the fire rating of the boiler. Of course they never gave me that in writing just verbal over the cell phone. That is 0.60 gph That's about 84,000 b.t.u.'s. so new boiler, hydraulic separator, or buffer tank.

NTL1991

Thanks

While the nozzle in 2001 (when the boiler was producing steam for the whole house) was a .75, it is currently a Delavan .85 GPH. I removed the nozzle assembly to check the electrodes when I had no-fire issues.



The three boilers are cleaned by my brother every year. He works for a heating service company, and he does the work on his free time. He cleans all three boilers, changes the oil filters, replaces the nozzles with what was in there before,  but he doesn't perform a combustion analysis. This is why the last analysis was in 2001, when I only had one boiler supplying the house,



The reason why I have three boilers (my 1st floor apartment uses this Weil-McLain, the 2nd floor has a LAARS Newport Oil Fired Boiler at 100K BTU, and the 3rd floor has a teeny tiny Superior Boiler 80K BTU gas fired boiler. The 275 gallon single oil tank was removed and two ~136 gallon tanks were installed. I wanted separate heating systems so everyone would pay their own utilities, no splitting of the bills, I wouldn't have to include oil cost in the rent, and no one complains its either too hot or cold.



In 2007, the LAARS and Superior were purchased and installed new when the steam system was ripped out. The Weil-McLain (about 8 years old then) was kept and converted to hot water for the 1st floor.



Also, it doesn't short cycle as badly as I would expect, In the middle of winter, I timed the boiler cycles. It was 25 degrees

outside and the boiler was warm.

It took 20 minutes for the furnace to reach the high limit of 180 degrees, the thermostat still calling for heat. (I bumped the T-stat to 72 or so during this) The burner stayed off for 10 minutes, using residual heat in the cast iron, with the circulator

running, and then fired back up again for 6 minutes to reach 180 again. This cycle would repeat until I turned the T-stat back down.



How bad is this cycling?

James Day_2

Downfiring

Charlie,

When did weil mclain tell you that  you can downsize by half the unit size.  Last time I spoke with them the told me 10%.  If I had known I could downfire that much it would have saved me some headaches.

EddieG

Downfiring

The key is what your combustion readings end up at when down firing. You can change nozzles, adjust pump pressure, and adjust air all day long. But your readings are the key. I haven't called W/M to see how much you can down fire and don't plan to. Because combustion readings are the key. But when I have down fired equipment to far my combustion readings go crazy. My point is, if you change nozzles you need to check the combustion readings, as they well change. So you really need someone to check the readings on those units. Anytime service is preformed a combustion test needs to be done.



As far as your situation with the 3 boilers. I understand why you separated them for utility purposes. But I think you would be further ahead setting them up to stage with an outdoor reset control. You could install a BTU metering set up to monitor each apartment. I am not saying rip everything out and start over, that would be to much of an investment. But you could work on it gradually in phases. The way it is set up now is wasting energy.



You could start with some controls on the boilers. Such as Heat Managers and then add Outdoor reset. Followed by some re-piping. If your set up was redesigned you could see as much as 30% fuel savings. With the price of oil going up your payback time would be minimal.

Steamhead

And

your quote "He cleans all three boilers, changes the oil filters, replaces the nozzles with what was in there before,  but he doesn't perform a combustion analysis" is scary. No one really knows how well and safely those boilers are running unless the required combustion analysis is done. And if something goes wrong, you as the landlord would be liable.



And, if they are set up properly, there shouldn't be much cleaning to do in the first place.  If they soot up during the season, that's costing you and the tenants money.



You need someone with the proper equipment to work on those boilers. Period.

NTL1991

Thanks

Thanks for the replies.



I'll have my brother run a combustion analysis when he cleans the boilers in the summer. He has the equipment, as he has the use it for the jobs he's called to. I guess in my case, because he's my brother, he's never thought there was enough reason to do it, and it would've been wasting time. As I've heard, this is incorrect, and I'll have him do an analysis on all three boilers.



I have been looking into Beckett Heat Managers, as my brother has spoken about them, and has installed one on my parent's boiler. I appears to have saved them in oil. I've been looking on eBay for a bit to find one that's not $300+ Also, I've done research on outdoor reset controls, but they all seem quite pricey. When the cold winter is over, I can go into the basement and drop the Aquastat's high limit for free... (Of course, without dropping it so much as to allow condensing).



When I had the original circa-1948 one-pipe steam system, I constantly had problems with the 3rd floor not getting enough heat, (which, by the way, one bedroom did not even have a radiator), the 2nd floor would be comfortably, and the 1st floor would be steaming hot. I purchased all new adjustable vent valves and spent time adjusting each one, and still couldn't get the system the provide even heat. Also, the fact that I had to divide up the oil bill each month and the fact that there were 3 thermostats, one on each floor, and if one person wanted heat, everyone would get it whether they liked it or not, were enough to put me over the edge.



 Mind you, when I first purchased the house and lived on the 3rd floor, It had one ~150 giant gas water heater which all three floors used, and was on the 3rd floor gas meter (the only gas meter in the house), along with the one shared gas clothes dryer which was also on the 3rd floor meter. The shared clothes washer was using the 2nd floor electricity. I had complaints of people leaving laundry in the washing machine and others couldn't use it... UHH! Everything was all over the place, and I had enough. I had gas meters installed for each floor, bought 2 new washers and 2 new dryers, brought the electrician in to wire everything in, a plumber to run gas lines to the dryers, and water/drainage to the washers.



So, I got quotes of $27,000 and $16,000 to remove the steam system and pipe all three floors with separate hot-water baseboard heating systems. The low bid plumber had done work for me before, and I've always been satisfied, so I chose him. Two new boilers were purchased (2nd floor - Laars Newport Oil @ 100K BTU/hr, and 3rd floor - Superior Boiler Gas @ 80K BTU/hr) and installed. I didn't want my walls torn up, so the supply and returns to the 2nd and 3rd floor were all run in PEX up through the bedroom closets which are aligned vertically. In some sections, the piping loops around inside the baseboard and goes through closets to get to the next room... The front hall on the 2nd floor has a "dummy" baseboard which hides the PEX pipes which run from the living room to the bedroom. I now actually have heat in the 3rd floor front bedroom...



Attached is a little set of plans I came up with while brushing up a little bit on my CAD skills.



Nick

mark schofield

teckmar

If you have a separate DHW system, the Teckmar 256 single stage boiler control isn't that expensive. The literature suggests that it has outdoor reset and you can adjust the differential to minimize short cycling.

NTL1991

I'll look that up.

Thanks. All three apartments have gas hot water heaters, so I'll definitely do some research on that controller. Having an outdoor reset built-in would be perfect. Does it also work as an economizer?

Steamhead

Yes it does

since you don't have to heat the water to full temperature on a milder day, you use less fuel. 

EddieG

I.....

I have dual boilers with a Tekmar staging / reset controller in my own home. I have recently added Beckett's Aquasmart controllers to each boiler. I can say what savings are yet, to new. But cycle rate has improved.



You have the ideal situation for the Taco or Istec modules. These modules would be installed in each apartment. You basically connect a boiler supply and return pipes. Then heating supply and return pipes from the baseboard loops. Then domestic cold and hot pipes. They measure BTU's at each apartment and domestic water usage. A really sweet set up for your application. It would simplify your system, lower maintenance cost, and improve efficiency.



Something to think about in the future. In the meantime, get the units tested, ASAP!