New Boiler suggestions

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Old 02-14-10, 03:35 PM
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New Boiler suggestions

I need a new oil boiler. MY 30 yr. old Weil Mclain needs to be replaced before the next heating season. I have baseboard heat in a 4,000 sq ft. house. My design heat loss is 95,500 (if I did the calculation correctly). The current boiler heats the house pretty well, it's a 4 section cast iron with a tankless coil and booster tank rigged with a circulator and is fired by a Riello F5 with a .75 nozzle. It runs 4 zones. The circulators and the controls have all been replaced over the last 4 years. From what I've been reading, a condensing boiler won't cut it. I have it serviced by an independent service guy and he is suggesting a 3 section Burnham (not a 3 pass) with an indirect for the hot water. I think he likes it because of the front door access for cleaning. I was thinking 3 pass cast iron with an indirect or maybe an EK 2000. Any opinions on any of this stuff? I have a good connection and can get a good price on the hardware and install it with help or have someone do it for me. I can get a good price on a Buderus or a Biasi or just about any American made boiler. Which system would you prefer if you were in my position? If I went with the EK system, I would probably give the job to a contractor to do the whole thing, at a much higher cost. What size would you use and would you add an outdoor reset? I would not use a logamatic on the Buderus because of the DHW priority, which I don't really care for. Sorry for the long question.
 
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Old 02-14-10, 03:58 PM
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I think you have come in way high on your heat loss calculation. Number two fuel oil has approximately 142,000 BTUs per gallon so firing at 100% efficiency would mean a .75 gph nozzle would give an ultimate of 106,500 BTUs per hour. Multiply that by a more reasonable 80% overall efficiency (it is probably lower) gives 85,200 BTUs per hour. This means that under design conditions your boiler would be firing constantly and you would not be able to meet your indoor design temperature.

I think that ALL residential hot water space heating systems should have some kind of reset, either an outdoor temperature reset or an indoor temperature reset.

I don't have any contemporary experience with residential boilers but I would suggest the three-pass for greater efficiency. If you choose the Buderus you do not have to have the indirect water heater on priority, you can connect it as just another heating zone.
 
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Old 02-14-10, 06:26 PM
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Thanks for the heads up on the heat loss. I redid the heat loss calc a little more carefully and it came out to just under 60,000, sorry about that. It was mostly the R value of the windows that threw it off along with some other things. I did run the boiler for four years with a 1.00 gallon nozzle and everything was fine as well. I think I saved some real money using the lighter nozzle, even though the boiler seemed to run a bit more often. It's hard to tell as the weather in New York form one year to the next has been all over the place. I used the calculator on builditsolar.com. Thanks
 
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Old 02-15-10, 07:58 AM
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I also like the three pass boilers. They are more efficient and usually quieter operating.
The MPO can accept 100f return water without a problem with condensation or thermal stress due to built in mixing.
 
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Old 02-15-10, 08:06 AM
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I believe that the Riello burners run at a higher oil pump pressure. Upwards of 200 psi. Although the F5 set up manual shows 145 psi. Which if is being used the .75 nozzle is pushing 0.9 gals per hour. Which puts the heat output (minus 20% loss) at around 101 K Btu/Hr.

Al.
 
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Old 02-15-10, 08:43 AM
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Thanks for your input guys. I did a few more different calcs for the heat loss, and they all come up slightly different. The best I can tell, the 60,000 figure is too low and the 95,500 is high. The average is about 80,000. The current boiler is a W/McLain A/B 668U rated 218,000 with 1.00 gph, net IBR of 198,000 with a tankless coil, I believe it's 4 sections. The last service, when the pump on the Riello was replaced (leaking) shows the pump pressure set to 150 with a .75 60 degree nozzle. When it's really cold, the boiler runs for longer periods and slightly more often. The DHW is not a problem, but one zone runs for a long time, It is the largest zone and has big openings to another zone. When both are set the same the boiler doesn't run as long and fires less often. We did have a 1.00 nozzle for a few years, but went smaller two years ago. The house has new windows and exterior doors 6 years ago and extra insulation in the attic (R19 on top of old R13) and the ceiling was insulated in the basement. I was looking at the Brookhaven study info and the EK and the "European" well insulated boiler were close (condensing and gas aside). Which boiler was that they used?
 

Last edited by MM1957; 02-15-10 at 09:28 AM.
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Old 02-15-10, 10:27 AM
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The Burnham MPO is available in a 74 K BTU (DOE), and a 129 K BTU size. The first one fires at .6 GPH with the larger one at 1.05 GPH. This is a 3-pass CI boiler.

Al.
 
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Old 02-15-10, 10:50 AM
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Thanks OB. If the 80K figure is the real heat loss of the building, would you size slightly larger considering the indirect I'll be adding or slightly smaller, figuring it's probably over done and boilers are more efficient the longer the run times are (assuming they eventually catch up). How do I figure in the indirect? The house is all of 4,000 sq.ft. with some large windows and I live in New York (Long Island) so the design temp is 10 or 15. There are 3.5 baths and 4 people. Oh yeah, and the dog (she's very efficient and doesn't use any hot water).
 
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Old 02-15-10, 03:28 PM
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I think there is now an 'in between' model of the MPO that OB mentioned... nice boiler...
 
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Old 02-15-10, 06:17 PM
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The MPO115 is 98k DOE output. Unless you have a huge hot water demand I would not up size the boiler for the indirect.

No offense to anyone but the different heat calc totals is the reason I always say the heat losses should be done by people who know how ti input the numbers properly. I appreciate people wanting to do things themselves but this is the most important step in the boiler replacement process and any errors you must live with the entire life of the boiler.
 
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Old 02-15-10, 06:17 PM
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Originally Posted by NJ Trooper View Post
I think there is now an 'in between' model of the MPO that OB mentioned... nice boiler...
In this case that would be a good choice. I need to update my info on the MPO (been eyeing up the MPO myself).

MM, if the heat loss is 80K BTU/hr, then the 74 K output boiler would not keep up on a design day. Add in an indirect, and seems (to me) that you will in trouble.

I am not an expert at boiler sizing. So do not feel comfortable proving any additional input on that area.

Al.
 
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Old 02-15-10, 07:07 PM
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Thanks everybody. I agree that the sizing should be done by someone who knows what they are doing. I'm a pretty good mechanic but as Mr. Rbeck stated, that is a decision I have to live with for the life of the boiler or until the kids are out of school and I sell the house, whichever comes first. Right now I'm just getting ideas about the type of system I want and the approximate size and cost. I need to replace my boiler before next season (I hope not sooner). The Burnham sounds like a solid unit and I'll look into that as well. Anyone else have experience with Buderus, Biasi or any other American made units? And that EK unit is still lurking in the background. I'm little leery about it because I've heard a lot of negative things about the flat plate heat exchanger. I like the Biasi because I think I can direct vent a unit big enough for my needs and not have to line my chimney with a stainless liner. I think I have a condensation problem with my current chimney, or some kind of water intrusion problem(only sometimes?) that I have to solve before I stick a new unit in my basement. I have to check on the venting requirements of everything else I'm looking at as well. I'm glad I have a little time for this stuff. I don't want to make an expensive mistake.
 
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Old 02-16-10, 06:19 AM
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Just two points the MPO also comes as a direct vent but unfortunately the sizes available are probably too larger for you situation.
You can power vent any boiler that does not have a power venter built into it already. I add that last part as there has been two jobs last year where the boiler was a power vent boiler and there was also an external power venter installed..... Yes two power venter's.
 
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Old 02-24-10, 09:52 AM
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Originally Posted by MM1957 View Post
The current boiler is a W/McLain A/B 668U rated 218,000 with 1.00 gph, net IBR of 198,000 with a tankless coil, I believe it's 4 sections. The last service, when the pump on the Riello was replaced (leaking) shows the pump pressure set to 150 with a .75 60 degree nozzle.
That is a 6 section boiler, its rating is based on a firing rate of 1.80 GPH. Quite a "heavy hitter" by today's standards. How much fuel does the boiler consume annually?

I have 6 section 66 series Weil McLain in my home, I'm firing it with an F10 Riello at 1.80 GPH.
 
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Old 02-25-10, 07:31 AM
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RobRoy,

Right now it's fired with a Riello F5 with a .75 nozzle. The numbers I gave were from the label on the side of the boiler and it's obstructed by the expansion tank (naturally) so it's very hard to read. Maybe it does say 1.8, but it sure looks like 1.0 gph. I'll have to try harder to read it. My boiler tech told me it was 4 sections, but he also suggested I get a new one pass boiler too. Luckily, I buy oil from someone else.

The amount of fuel it burns is all over the place because we get some really mild winters and some really nasty ones with no definite pattern. When I bought the house it had a 1.0 nozzle (the burner is probably 15 yrs old and the boiler is 30) and last year we downsized it to .75. It seems to run for longer periods but I haven't burned more (or less) oil than last year. I got filled up at the end of October and In mid January it took another 250 gallons (I have two 330's in my basement) so I used about 3.33 gallons per day average over that time (250 gal/ 75 days = 3.333) which isn't too bad for the winter in a 4,000 sq. ft. house. I have 4 zones of baseboard and a tankless coil and the thermostats set back to 62 at night and during the day on weekdays. I agree, it's a beast by today's standards. If I'm heating the house with a .75 nozzle and only burning 3.5 gallons a day I'm sure I could get by with a unit rated for less than 100,000 BTU/hr. and heating a lot less iron and water. It's running about 4.6 hrs per day average during that time (3.33 gph X 1.333) and that's with a tankless/storage tank for dhw. I think I'll do better with a small indirect as a fifth zone. I wouldn't replace it except that it has a leak. The house is 45 years old, so there was another unit here originally as well. I don't know what it was but it has a pretty big footprint and only lasted about 15 years. I'm sure oil was really cheap in the mid sixties.
 

Last edited by MM1957; 02-25-10 at 09:15 AM.
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Old 02-25-10, 04:16 PM
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Rob Roy,

Actually, your post made me go back and look at my oil bills and it turns out that I used less oil two years ago, when the nozzle was 1.00 gph. I'm missing some oil bills from last year, so I'm not sure about last winter. I remember looking at the bills last year and there wasn't much change from the year before. Could be just the kind of winter we had or maybe the boiler works better with a hotter gun. My usage was a little under 3.0 gal. per day for most of the winter (lower after and before that). I'm not sure how to use degree day info to see which winter was worse, assuming I can find it.

I wonder if any of this has anything to do with the condensation in my flue pipe, a recent problem. It may have started happening last year when we went to a smaller nozzle. Anyway, I need to change the boiler soon anyway and the newer boilers have lower stack temps (or so I'm reading) so I gotta do the liner thing or direct vent anyway.

Just curious, how much oil does your F10 burn in your house? How big and leaky is your house?
 
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Old 02-25-10, 04:58 PM
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Look at Pensotti..... their quatech series is pretty impressive. I have the DK2-4 using a 41 gal boiler mate on 3 zones plus the DHW.

http://www.pensotti-pna.com/Heatline%20Quatech.pdf
 
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Old 02-25-10, 04:59 PM
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Heating & Cooling Degree Days - Free Worldwide Data Calculation

I would try taking the total number of degree days for each heating season and divide that by gallons of oil used. That should get you where you want to be.
 
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Old 02-25-10, 06:39 PM
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I wonder if any of this has anything to do with the condensation in my flue pipe, a recent problem. It may have started happening last year when we went to a smaller nozzle. Anyway, I need to change the boiler soon anyway and the newer boilers have lower stack temps (or so I'm reading) so I gotta do the liner thing or direct vent anyway.

Just curious, how much oil does your F10 burn in your house? How big and leaky is your house?
The first number in the boiler model is the number of sections, the second is the series. e.g. A Weil McLain 468 is 4-sections, and in the 68 boiler series. If your boiler is a 668, then it is indeed a 6-section unit. The chamber in that beast is about 18" deep .

I wouldn't be surprised if the condensation is from an internal leak between the sections, that would cause a lot of moisture to go up the stack. Do you see any steam coming out of the chimney? If you think the condensation started when you down-fired the boiler, I wonder if it takes a long time to get above condensing temperatures?

What do you have for a chimney setup? It is masonry? Inside or outside the home? Depending on the chimney dimensions and the boiler you choose, you may not need a liner.

As for my "antique" boiler, I'm heating a 100 yr old farmhouse with it, and DHW with a 30 gal. indirect. Overall I consider the house pretty well insulated and airtight for its age. Between Oct. 5th and Dec. 5th I burned 160 gallons of No. 2 fuel; after that I fired up the coal boiler and the Riello has been quiet.

The Riello was a nice upgrade, even thought the "universal" mounting flange didn't fit and I had to make a custom mounting plate. Previously the boiler was fired with an old WM branded burner @ 1.25 GPH. Despite two technicians working on it, the boiler was always sooted up, and we occasionally ran out of hot water. Now the heat exchanger stays very clean, and the hot water recovery is excellent. Stack temperature was 480F after the Riello install, and the boiler is vented into the original 1910 unlined brick chimney.

As long as I'm running the coal boiler and the old Weil McLain can remain on standby, I see no reason to replace it.
 

Last edited by Rob Roy; 02-25-10 at 06:41 PM. Reason: spelling.
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Old 02-25-10, 09:54 PM
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I've been seeing a lot of steam or white smoke out of the chimney the past few days. It could just be the weather, it's been between 35 and 40 for the past few days and really damp and rainy. As I write this it's 33 and 90% humidity and there's a bunch of white smoke coming out of the chimney. The snow just started coming down after raining steady since last night.

The chimney is lined masonry attached to the back of a one story section sticking out of the back of the house, It's original and is in very good shape, re-pointed 7 years ago when we bought the house. I didn't measure it today but I would say the tile flue 10 inches square.

I'm thinking that the chimney is OK and the problem is from the boiler leak, between the last two sections in the back, high right. From the inspection port you can see the leak run down into the chamber as the boiler runs after being cold for a little while. It starts to drip on the floor after being cold for an hour or two. It hasn't been a problem as the boiler maintains heat to keep the aquastat happy, even in the summer (tankless coil/storage tank). I do set the stat lower when I turn off the heat in the spring.

I'm hoping that the leak is the cause of the condensation. I'm trying to catch the drip to see exactly when it happens, but I keep missing it. I think it's happening early in the morning when the Tstats start the system early to bring the temp up gradually. I took of the stack this afternoon and looked inside the chimney in a driving rainstorm and it was dry all the way up and the tile looked pretty good. There was white scale on the inside of the horizontal run of the stack to the wall and a white drip mark on top of the boiler jacket below where the elbow meets the that run. I wiped up the drip yesterday and it was clean when I went to bed. The stack is new about two months ago. The chimney was pretty clean. I think the condensation is only in the stack.

Coal huh. Do you have to feed it yourself or do you have some kind of a stoker that feeds it automatically? Sounds pretty cool (or warm), I guess coal is cheaper than oil?
 
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Old 02-27-10, 09:25 AM
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I agree that your condensation problem is from the internal boiler leak.

I sent you a PM regarding burning coal, I don't want to hijack the thread.
 
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Old 02-27-10, 04:17 PM
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Anyone have any experience with the Beckett Aquasmart boiler control or the B & G Grundfos Alpha circulator pump?

I'm starting to get some quotes about replacing my system and the Aquasmart was proposed as a boiler control and the Alpha to replace my 4 Taco circulator pumps, which would be 5 to add the indirect DHW unit.

I assume that you use zone valves to open each zone as heat is called for instead of multiple pumps, but is it standard practice to use a zone valve with an indirect? I guess it's just another zone to the boiler. The Alpha has an adjustable output to match whatever the load is. Will it handle 5 zones including a split loop on the second floor if they all call at the same time?

I'm told the Aquasmart reads the drop in temperature between the boiler temp and the return water from the zones to adjust the high limit, without regard to the outside temperature and conditions. Sounds like a good idea. I'm also told that in New York State that some sort of smart control will be required within a couple of years. I'd go in that direction anyway.

Thanks to all for the input and information so far.
 
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