New Weil Boiler

corgi11

Old rating plate said 73000 water nothing on the tag said anything about steam.

jesmed1

corgi11 said:

LRCCB Why don't you think a new boiler with 73k ibr net won't work where the old boiler of 73 k net worked? This setup has worked for the 37 years I have owned this house.

He's not saying it won't work, he's saying it's sized just right for your design temps. However, he is pointing out that if you have sustained high winds at -10 degrees, the "wind chill" will cool the house a lot faster, and you might not be able to maintain 75 degrees on that extreme day.

But if you did have an extremely windy day at -10 with your old 73k IBR net boiler and it did manage to maintain 75 degrees anyway, then your new boiler should keep up too.

corgi11

Old boiler 1953 arcoliner had 1 plate on it. 1 gph oil. Underneath it it said 73000 BTU water. Under where the word steam was was blank. Again there was no steam rating on this boiler only water. Old boiler is gone

corgi11

Thanks again for all your help.

jesmed1

corgi11 said:

Old boiler 1gph(140k)BTU 73000 water out was fine for -10 day kept house at 75. 100 ft baseboard set with limit at 205. If you look at slant fin fine line 15 it shows 680 approx BTU ft.

That's the BTU output at 200 degrees. But since your boiler limit is set only a bit higher at 205, the boiler hits its high limit just after the radiators are putting out the full 68,000 BTU hr.

And in fact, your high-limit condition proves that your radiators may not be putting out quite as much BTU's as you think, because the 73,000 BTU output from your boiler is not being radiated away fast enough even with 200+ degree water to prevent the 205 limit from being reached.

Ideally you'd want more radiation so that you could radiate the full 73,000 BTU/hr without getting close to the 205 high limit.

Again, it's not that important, but your question was why your new boiler is hitting its high limit, and that's why. Your new boiler is pumping out heat faster than the radiators can reject it, even at 205 degrees. And your old boiler may have been downfired when converted to gas so that it was putting out fewer BTU's than the rating plate.

corgi11

Jesmed I used those slant fin numbers as a reference only.
Old triad baseboards 6 inch high fins spaced 1/8 inch apart. Steel Covers. Only slots in top front of covers. It takes a long time for the air to convect to start to heat rooms. Water enters at bottom of baseboard makes u turn and exits top of baseboard.
I really think with this description of my actual base boards they really emit more than the slant fin. Just longer to heat up.

jesmed1

corgi11 said:

Jesmed I used those slant fin numbers as a reference only.
Old triad baseboards 6 inch high fins spaced 1/8 inch apart. Steel Covers. Only slots in top front of covers. It takes a long time for the air to convect to start to heat rooms. Water enters at bottom of baseboard makes u turn and exits top of baseboard.
I really think with this description of my actual base boards they really emit more than the slant fin. Just longer to heat up.

OK, maybe so. But back to your original question of why the new boiler is hitting its limits, again, it's because your new boiler is heating the water faster than the radiators can reject the heat, even at 205 degrees.

Your old boiler never got the water hotter than 150 or so, and that's a big difference. On the slant fin chart, the heat output of a slant fin changes by almost a factor of two from 150 degrees to 200 degrees.

This strongly suggests to me that your old boiler actually had a lower BTU input rate than shown on the rating plate when it was converted to natural gas. Maybe the original owner realized the boiler was putting out more heat than was needed, and he had the installer size the gas orifice for a reduced BTU input.

corgi11

I am a retired communications engineer and don't normally do heating work. I really appreciate all your answers. But I think if my total radiation is somewhere around 73k BTU and my boiler output ibr net is around 73k BTU then the "dead men" who plumbed and installed my heating did something right.

jesmed1

corgi11 said:

I am a retired communications engineer and don't normally do heating work. I really appreciate all your answers. But I think if my total radiation is somewhere around 73k BTU and my boiler output ibr net is around 73k BTU then the "dead men" who plumbed and installed my heating did something right.

Yes, please don't take my comments as criticism. Your heating system is sized better than 99% of the houses in America, probably. Just thinking through why your new system is apparently acting different from the old one.

corgi11

Jesmed on -10 degree day old boiler was hitting high limit at 205.

jesmed1

corgi11 said:

Jesmed on -10 degree day old boiler was hitting high limit at 205.

OK. Well, that further proves my observation that you don't have enough radiation to prevent *either* your new (or old boilers) from limiting out at 205 degrees.

Again, it's not necessarily a problem, just an observation. Your old boiler took longer to heat up and eventually limit out, possibly because it had a lower BTU input rate, and also more mass in the heat exchanger. Your new boiler has less mass and heats up faster, so it reaches the limit temp sooner.

But in both cases, you don't have enough radiation to prevent either boiler from high limiting, sooner or later.

corgi11

Jesmed thank you for all your help but I really think I have a mass problem with only 2.5 gal of water in the boiler. It took so long for the old boiler to heat that the baseboards were up and cooking by the time the tstat was satisfied. Now the boiler is up to high limit quickly
waiting for the baseboards to catch up. I will get back to the group when the temp gets really cold outside.
Again I thank everyone for all their help 

jesmed1

corgi11 said:

Jesmed thank you for all your help but I really think I have a mass problem with only 2.5 gal of water in the boiler. It took so long for the old boiler to heat that the baseboards were up and cooking by the time the tstat was satisfied. Now the boiler is up to high limit quickly
waiting for the baseboards to catch up. I will get back to the group when the temp gets really cold outside.
Again I thank everyone for all their help 

I'm not a heating expert, but you might find that you need a higher circulator speed to increase the rate of heat transfer from the boiler to the baseboards. Here's a short thread on that subject:

https://terrylove.com/forums/index.php?threads/circulator-pump-setting.16581/

And another more lengthy discussion:

https://forum.heatinghelp.com/discussion/167500/pump-speed-that-creates-the-largest-delta-t

corgi11

Thanks again Jesmed 1
My delta t on old and new systems less than 10 degrees. I am using equivalent pump old and new systems. Delta t about same old and new systems. Original pump B &G series 100. I replaced when it died with a pump that would move more water into a high dynamic head for my half inch lines. Used higher head water cooled pump for almost 25 years. Using equivalent pump on new boiler.

LRCCBJ

jesmed1 said:

LRCCBJ said:

corgi11 said:

Don't you size boiler for design temp in my case -10.
I did modified j calc and ane up with around 68000 btu. 1953s house all vaulted ceilings all brick virtually no insulation. I could have gotten the smallest boiler weil had it is 20k ibr less BTU then I have now but 20k BTU is only 4 electric space heaters spread over my entire house!

With a manual J of 68,000 and a net output of the new boiler of 73,000, the sizing is just about perfect. Any suspicion that it is oversized is incorrect. The net output of the next size CGa-3 is 48,000 and you'd freeze to death at -10F.

I don't doubt that his heat loss calculation is correct. But it sounds like he doesn't have enough radiation to be a good match with this boiler, because the boiler is high limiting before the Tstat satisfies. He also says it takes a long time to feel hot air convecting up from the radiators, which is another data point suggesting insufficient radiation.

Couple of things:

1) His description of the baseboard leaves me in a bit of a quandry. They may be a bit larger than we have concluded based upon the 600 BTU/ft assumed.

2) A baseboard typically heats up almost instantly due to the low mass. If it "takes a long time" this indicates a flow problem..........or a temperature problem...........not an insufficient radiation problem. Be interesting to see the temperature of the baseboard at the point where the boiler hits limit.

3) Do we know the boiler is set to a 180F limit? Set it lower than 180F for efficiency in warmer temperatures and it is certainly going to reach limit before the 'stat satisfies. It's always too large at any outdoor greater than design. That's the way it is with a fixed output boiler. Those that choose to use outdoor reset will, by definition, suffer with much greater cycling.

LRCCBJ

corgi11 said:

Old boiler 1gph(140k)BTU 73000 water out was fine for -10 day kept house at 75. 100 ft baseboard set with limit at 205. If you look at slant fin fine line 15 it shows 680 approx BTU ft. I know my baseboard probably puts out more. 

LRCCB Why don't you think a new boiler with 73k ibr net won't work where the old boiler of 73 k net worked? This setup has worked for the 37 years I have owned this house.

Sorry if I confused you.

The new boiler will work fine. It MIGHT be insufficient, based upon your Manual J calculation when the Chicago temp goes to -10F and the wind goes to 40 kt. This situation is, obviously, extremely rare and you probably would easily accept a drop to 65F under such conditions.

I have a setup in one house that uses a 75K HWH, via a FPHX, to heat the building. The Manual J shows a heatloss of 45000 @ 6F. When the building goes down near 0F (a rarity), the indoor will fall slightly to 65F overnight. The estimated net from the HWH is only 50K. The error is very likely the additional losses generated by wind AND the fact that the HWH does hit the limit of 135F on the return in such situations (CI radiation insufficient with 148F supply at 0F ambient).

LRCCBJ

corgi11 said:

Jesmed on -10 degree day old boiler was hitting high limit at 205.

This is an interesting data point. The assumption of the output of the baseboard was based upon a temperature of 180F. 205F is a completely different ballgame.

Do you know where you set the high limit on the new boiler?

LRCCBJ

corgi11 said:

Thanks again Jesmed 1
My delta t on old and new systems less than 10 degrees. I am using equivalent pump old and new systems. Delta t about same old and new systems. Original pump B &G series 100. I replaced when it died with a pump that would move more water into a high dynamic head for my half inch lines. Used higher head water cooled pump for almost 25 years. Using equivalent pump on new boiler.

This, effectively, rules out a flow problem. But, it would be advantageous if you could get a reading on the BB with an infrared gun when the boiler reaches HL. The first length of baseboard should be very close to HL. If you still do not "feel the heat" check for anything that is blocking the airflow beneath the baseboard...........carpet, typically.

corgi11

New boiler set 205. The steel covers get very hot after a while. The system has separate run and return for every room. Worked fine for my 35 year residency. No carpet problem cleaned baseboards as best I could. Since there is only slots at the top front of the baseboards I can't get a gun reading. The baseboards were in use 35 years before I got the house no way to take off steel baseboard covers. But I can tell you at 205 boiler Temp you will burn your hands on the baseboard covers and you will feel the convection. Because of the design of these baseboards they convect slower than modern baseboards but eventually get to radiation,  at 205 at -10 my house is fine at 75. I have balanced the heat in each room run so that each room is the same.

jesmed1

LRCCBJ said:

corgi11 said:

Thanks again Jesmed 1
My delta t on old and new systems less than 10 degrees. I am using equivalent pump old and new systems. Delta t about same old and new systems. Original pump B &G series 100. I replaced when it died with a pump that would move more water into a high dynamic head for my half inch lines. Used higher head water cooled pump for almost 25 years. Using equivalent pump on new boiler.

This, effectively, rules out a flow problem. But, it would be advantageous if you could get a reading on the BB with an infrared gun when the boiler reaches HL. The first length of baseboard should be very close to HL. If you still do not "feel the heat" check for anything that is blocking the airflow beneath the baseboard...........carpet, typically.

Something doesn't add up here. corgi11 says the delta T on the new system is 10 degrees, same as the old system. That means the radiators should be heating up now just as fast they did with the old boiler, no?

Unless something changed drastically after the new boiler was installed and the delta T of 10 degrees was measured, and now there's some flow restriction that wasn't there when the delta T was measured initially.

corgi11

What changed drastically is my old boiler held much more water and took much longer to heat up because there was so much more cast iron. My triad baseboards warmed up as slowly as the boiler did and warming together satisfied the tstat. Now the new boiler holds 2.5 gal and gets to temp pretty quickly. I am quite sure after bouncing off the high limit the house will be as warm as it always was. Just way smaller mass boiler.

LRCCBJ

jesmed1 said:

LRCCBJ said:

corgi11 said:

Thanks again Jesmed 1
My delta t on old and new systems less than 10 degrees. I am using equivalent pump old and new systems. Delta t about same old and new systems. Original pump B &G series 100. I replaced when it died with a pump that would move more water into a high dynamic head for my half inch lines. Used higher head water cooled pump for almost 25 years. Using equivalent pump on new boiler.

This, effectively, rules out a flow problem. But, it would be advantageous if you could get a reading on the BB with an infrared gun when the boiler reaches HL. The first length of baseboard should be very close to HL. If you still do not "feel the heat" check for anything that is blocking the airflow beneath the baseboard...........carpet, typically.

Something doesn't add up here. corgi11 says the delta T on the new system is 10 degrees, same as the old system. That means the radiators should be heating up now just as fast they did with the old boiler, no?

Unless something changed drastically after the new boiler was installed and the delta T of 10 degrees was measured, and now there's some flow restriction that wasn't there when the delta T was measured initially.

At 205F with a 10 DT, the system output is nearly 750 BTU/ft. 100 ft equals 75K. That's the net output of the boiler.

I agree...........something doesn't add up here.........but the boiler is perfectly sized.

corgi11

Thank you guys for all your help. I am going to sign off until heating season here in Chicago. I will get back to you guys to let you know what's going on and if I need to take up a collection to keep me warm.
Again thank you everyone for your help and advice.

jesmed1

LRCCBJ said:

jesmed1 said:

LRCCBJ said:

corgi11 said:

Thanks again Jesmed 1
My delta t on old and new systems less than 10 degrees. I am using equivalent pump old and new systems. Delta t about same old and new systems. Original pump B &G series 100. I replaced when it died with a pump that would move more water into a high dynamic head for my half inch lines. Used higher head water cooled pump for almost 25 years. Using equivalent pump on new boiler.

This, effectively, rules out a flow problem. But, it would be advantageous if you could get a reading on the BB with an infrared gun when the boiler reaches HL. The first length of baseboard should be very close to HL. If you still do not "feel the heat" check for anything that is blocking the airflow beneath the baseboard...........carpet, typically.

Something doesn't add up here. corgi11 says the delta T on the new system is 10 degrees, same as the old system. That means the radiators should be heating up now just as fast they did with the old boiler, no?

Unless something changed drastically after the new boiler was installed and the delta T of 10 degrees was measured, and now there's some flow restriction that wasn't there when the delta T was measured initially.

At 205F with a 10 DT, the system output is nearly 750 BTU/ft. 100 ft equals 75K. That's the net output of the boiler.

I agree...........something doesn't add up here.........but the boiler is perfectly sized.

Bottom line is that the boiler is heating the water faster than the radiators can cool it, even at 205 degrees. So either the radiators are outputting less heat than we think, or the boiler is outputting more heat than we think. Another possibility is that the high limit switch on the boiler isn't calibrated properly, so the boiler is actually limiting out at, say, 190 even though the high limit is set at 205. So the boiler limits out before the radiators get hot enough to reject the boiler's 73k BTU/hr.

And the 73k IBR rating assumes the the standard 15% take-up and piping loss in his system, but maybe it's less. A 100,000 BTU input furnace running at 85% efficiency outputs 85,000 BTU net, and say the take-up loss is only 7%. Then the furnace is actually delivering close to 80k BTU to the radiators. And if the radiators are a little on the low side, say radiating 70k BTU at 205 degrees, there's your mismatch, and the boiler will always limit out.

EBEBRATT-Ed

@corgi11

If your hitting high limit that means the boiler is putting more heat into the system than the baseboard can output. That's the bottom line.

If you are sure that nothing is air bound and the air flow openings around the baseboard are clean and not filled with dirt, dust or the kids crayons then take a water temp measurement on the boiler supply and return at the same time when the boiler is running and has reached steady state. You want this temp to be around 20 deg or less. If it's over 20 your circulator is probably undersized.

To keep the boiler from hitting high limit you may be able to downfire it slightly but this must be checked with combustion test instruments.

The boiler puts heat into the system and the system gives off heat to the rooms. These two things are always trying to balance each other. The baseboard it what is in charge of the boiler.

corgi11

10 degrees delta

jesmed1

corgi11 said:

10 degrees delta

So your flow rate is good, but the boiler is still making heat faster than the baseboard can output it. You mentioned you installed an upgraded pump. How many gpm do you figure it's pushing through?

EdTheHeaterMan

I carefully read the all answers and comments you posted and believe that your 100,000 BTU Weil McLain is probably the proper size. I also believe that there are some problems that may relate to the actual condition of the radiators, or the flow rate of the water in the system, or both

At a 10°∆T during the heating cycle when everything is operating at steady state, Your flow rate of the water may be a little off from the design ∆T of somewhere closer to 20°. The other factor might be that the baseboard convectors are clogged with lint or dust bunnies from years of air flow. You will want to look at the bottom of the baseboard convector fins. I have actually increased the heating output of the system by vacuum cleaning all the baseboard fins by removing all the front covers and placing a brush attachment on a vacuum hose to remove the dust from the bottom of the convector fins. Once the front covers were replaced and there was at least 1" of air space under the front cover and no other restriction, the ∆T of the system from boiler supply to boiler return increased By 7° No other changes were made. The only difference was the increase in air flow thru the convector fins.

Since most baseboard convectors today have aluminum fins spaced about ¼” apart, and your fins are spaced ⅛” apart, there is a good chance that your baseboards have a greater BTU output per foot than say SlantFin 15. That is because there is more surface area for heat transfer per lineal foot of radiator. But if you restrict the airflow, then you decrease the output. And the fact that the fins are closer together, there is a greater chance of collecting dust on the bottom surface of the fins

Here is a good video for baseboard fin cleaning. https://www.youtube.com/watch?v=ItJj1sHMsXc

corgi11

Old triad baseboards 6 inch high fins spaced 1/8 inch apart. Steel Covers. Only slots in top front of covers. It takes a long time for the air to convect to start to heat rooms. Water enters at bottom of baseboard makes u turn and exits top of baseboard. These are almost impossible to clean correctly. Where modern baseboards have the louvers ,in my baseboards I have slots in the baseboard where the louvers should be.. The element area is attached to the back plate and you can’t remove it. The covers are one solid piece and are not removable especially after 70 years of use. I blew and sucked all I could from the baseboards. Because of the covers being steel with slots it takes longer for the air to convect then a modern design baseboard. The inlets have a lot of room and let air in. I live in a 4 square block area where all of us have the same baseboards. I was the last guy to get a new boiler. All our original boilers had the same ratings. No dampers in baseboards, my baseboards and covers get screaming hot at 205 degrees. Actually eventually the baseboard covers radiate heat as well as convect. Last time I checked delta t was less than 10.All of us also have the same baseboards and pump. Triad baseboard was very common Chicago Area in the 1950s. The exit area of the baseboards seems to be less than the standard modern baseboard so it takes longer to heat but if it is up and cooking it works fine. 75 degrees in my house at design temp of -10 degrees.

EdTheHeaterMan

Can you post a photograph of your baseboard radiators?

corgi11

corgi11

Fins are 6 in tall aluminum, copper pipe, steel covers Pipe is 1/2 inch diameter. Runs through top of fins makes u turn at the last fin and runs back through all the fins at the bottom of fins to boiler.

Fins are 1/8 inch apart. They go all the way from near the floor to where the slots start.

neilc

That wall to wall carpet is getting too close to your front cover,
an inch or better is required to let cool air in the bottom, and hot air out the top,
consider cutting the carpet back, and away into the room, to allow an inch of free air there, expose the subfloor. if you have hardwood, ok, or paint the subfloor flat black, or your choice, and have the tack strip reset forward.

Then you still want to inspect and likely blow out those fins,
like the video suggests, a shop vac sucking at the bottom, and an air compressor, nitrogen tank blowing down thru,
can you see to get the front cover off ?

corgi11

I have checked these baseboards for 35 years and can't find a way to take them off. The picture is misleading there is about an inch of clearance from the carpet to the bottom of the baseboard. Using high pressure air to blow from the bottom and shop vac to suck as much fro top as I can. Baseboards are 79 years old.

pecmsg

Post a picture of each end from a distance.

neilc

corgi11 said:

Using high pressure air to blow from the bottom and shop vac to suck as much fro top as I can. Baseboards are 79 years old.

the inch is minimal, but should work,
room air is sucked into the bottom, hot air comes out the top.
The air going into the bottom deposits dust and danders on the bottom of the fins also,

Blow down from the top, and suck from the bottom,
go back and forth a couple times,
top to bottom, bottom to top, rinse repeat.

if you can see fins inside, there ought be a way to open the front,
unless you're looking at cast fins on the backside of that face.
show a picture of an endcap, or inside corner,
and if you can get a closeup of the fins

neilc

and you might as well show a picture of the boiler, and the piping, and the circ(s),
all in one if you can, floor to ceiling

corgi11

Just needed specs on this 70 year old baseboard. Thanks for your time. BTU output at different temp water. Triad Baseboards.

neilc

No,
you're sucked in now,
pictures man,
pictures

hot_rod

jesmed1 said:

corgi11 said:

LRCCB Why don't you think a new boiler with 73k ibr net won't work where the old boiler of 73 k net worked? This setup has worked for the 37 years I have owned this house.

He's not saying it won't work, he's saying it's sized just right for your design temps. However, he is pointing out that if you have sustained high winds at -10 degrees, the "wind chill" will cool the house a lot faster, and you might not be able to maintain 75 degrees on that extreme day.

But if you did have an extremely windy day at -10 with your old 73k IBR net boiler and it did manage to maintain 75 degrees anyway, then your new boiler should keep up too.

I don't think houses feel "wind chill:) ?

Wind will add infiltration load, anywhere air can leak into the structure.

But the temperature will be the same on the outside of the home weather the wind is blowing or not