Heating Slow, Uneven, and Noisy

NTL1991

Hello. My house (1948 uninsulated colonial style) was originally steam throughout (3 floors, 3 apartments) and I had the whole steam system removed and replaced with 3 individual hot-water baseboard systems. The steam boiler, a Weil-McLain SGO-4, rated at 131K net BTU/hr (hot water), was converted to hot water use and heats the 1st floor apartment which is about 900 heated square feet.



The 2nd floor, which is identical to the 1st floor in size and layout got an oil-fired LAARS ~90K net BTU/hr boiler. The 3rd floor, which is roughly 650 square feet with cathedral ceilings and 6 skylights got a Superior natural gas fired boiler rated at 84K net BTU/hr.



Now, I'm pretty sure the 1st floor boiler is WAY too big for the size of the apartment, and it doesn't help that the baseboards were run in series, and of course, the bedrooms are the last two rooms on the loop. These two bedrooms get pretty cold at night even though the living room and dining room (at the beginning of the loop) at toasty warm. Using Taco Circulator's FloPro Designer software, it seems that my baseboard area is barely enough to make up for the heat loss through these uninsulated exterior walls. According to the program, I have roughly 35K BTU/hr of heat loss, thats taking into account the building materials. The heat loss for each bedroom is 6600 BTU's, and with the 12 feet of linear baseboard in each, thats just about exactly what needs to be there, assuming 550BTU per foot.



So, I decided to do some reporting last night while it was 25 degrees outside. Being that the basement below the 1st floor is very tight, all the windows are new double-glazed, and the floors above are heated, the temperature stays relatively constant.  At 12:50AM, the thermostat read 67 degrees. The furnace kicked on earlier, but is programmed to drop to 66 degrees after 11:30PM. So, I bumped the temperature up to 69 degrees. It took 20 minutes for the furnace to kicked off when the boiler reached 180 degrees, the thermostat still calling for heat. The furnace stayed off for 10 minutes, running on residual heat, with the circulator running, and then fired back up for 6 minutes to reach 180 again In order to raise the temperature 2 degrees, from 67 to 69, the furnace kicked on 4 times. It took 1 hour 10 minutes in total.



Should it take this long to raise the temperature 2 degrees when it's 25 outside?



Also, the system is completely noise free UNTIL about 45 seconds after the furnace kicks off when reaching 180 degrees. Then, with only the circulator running, the gurgling happens for about 5 or 7 minutes, stopping a bit before the boiler fires back up. The circulator is on the return side of the system, if that makes a different. The expansion tank is fine, no ruptured diaphragm.



Any advice. If (When, actually) this Weil-McLain goes, what is the proper size furnace that I would need. I would definitely switch to natural gas for the convenience factor.



Thanks,

Nick

NRT_Rob

well

35k load on less than 1k square feet is pretty extreme. poorly insulated?



all of your boilers are likely wildly oversized. I doubt you have more than a 25k load for any apartment here.



baseboard isn't really fast response heat though so taking time to get up to temp isn't crazy. perhaps you have a flow issue though that might explain the cold bedrooms and perhaps some gurgling noises as well... air, is often a likely culprit there.

NTL1991

True

Yes, after calculating with all three apartments and basement along with lowering the default winter room conditions to 68 degrees (the average heating temperature for my apartment), the heat loss for the floors are 24.8K (1st floor), 24.5K (2nd Floor), and 23K BTU/r (3rd Floor).



I know the house is tight, as far as air movement (I regularly get quite a bit of condensation on most of my windows on the 1st floor throughout the winter), but all of the walls are completely uninsulated (meaning a wall r-value of roughly 4 or so).



As far as new boilers, is there a certain percentage that is normally added to the total calculated heat loss in the house, like 10 or 15% more than the actual loss? I know the design conditions are set for the coldest day of the year.



I know there's no way of comparing the evenness of the new heating systems to the huge amount of radiant heat from the thirteen massive cast-iron radiators that were originally installed in the house. Perhaps it is the air in the lines, but I'm not sure where its coming from. I've bled the 3rd floor before and replaced a defective expansion tank, and bled again after replacing it (there was no isolation valve on the supply side of the furnace), but I cant seem to understand why the gurgling only happens after the furnace turns off... Perhaps the high temperature & pressure at 180 degrees allowing the air bubbles to expand in size?



Attached is the rudimentary plan that I created of the house.

https://docs.google.com/leaf?id=0B1Hbay0RJEcBMTJmNTg4NDEtYTU1OC00Yjg4LWI4OGEtMDJmZmFiMWNhM2Mw&hl=en&authkey=CJPn_M8F





Nick

NRT_Rob

wow

maybe 35kBTU isn't all that extreme then.



if you haven't already fudged yourself in the heat load, a 10% allowance is acceptable. of course often you still can't size a boiler to hit that optimal load...



do you get noise of any kind at the beginning of a heat cycle? tinkling, maybe?

NTL1991

Bleeding

Thanks.



I only get a very small amount of trickling noise (for maybe a minute) and it's only at the beginning of the very first radiator in the loop. I had to actually put my head near the radiator to hear it.



The real trickling comes about a minute after the furnace reaches it's high temperature cutoff. Then the trickling is very apparent, and sounds almost like water falling in a pipe.



I've bled the air out three times before, the 1st time not having any success at all, the second time, getting air noises at a couple plastic 90 degree elbows in the return line. (The pipes are 3/4" oxygen barrier PEX). Copper is used in some places to link one radiator to another. The 3rd time, the air was completely gone.



It seemed that my timing had to be perfect, as far as shutting the automatic fill valve and closing the drain cock on the return line (above the circulator) If I closed the automatic fill valve before shutting the drain cock, I'd get air in the system. It usually helped if I completely shut the drain cock with the fill valve still open slightly.



What is the proper way?



Thanks,

Nick

Ironman

Common Flue?

Please tell me that my eyes are wrong. Are the gas and oil boilers sharing a common flue liner?

NRT_Rob

hard to see for sure

but I think your pump may be pumping into the boiler, then into your expansion tank.



If so, then you are not 'pumping away' from the expansion tank and it's likely that this may be causing air problems for you. I can't pretend to know why it's showing up AFTER the zone stops though, that's odd. maybe the air is coming out of solution while you are pumping, and when you're done, the air is migrating to the high points... but I'm guessing a little there.

NTL1991

Yikes

Ironman, all three boilers are using the same flue liner... Also, the three gas water heaters are using this same flue, too. Is this a problem? (Of course, it sounds like it is based on your post!) I just had the chimney cleaned and inspected and the only thing they told me was that I might want to reline the flue down the road... But everything else checked out...



The oil furnaces are the two lowest when entering the chimney. The gas boiler and water heaters enter above, if that makes any difference. Doing some quick research, it seems as though the only restriction (NFPA 211) is the use of solid fuel along with gas in the same flue... Am I mistaken?



I believe I found the cause of the air. The bleeder cap on the air scoop was tightly sealed. Once I unscrewed the cap, a nice long hiss of air was released. Now, I'm not getting any gurgling or sound whatsoever in the system. Yes!



Nick