residential boiler choices

[maccardi]

I have 120 year old Victorian home, 4000 square feet 10’ ceilings with HW baseboard heat. I’m looking to replace the current boiler (CI 100Kbtu net) with a something new. I’m having a hard time keeping a 66 degree set point when the weather outside goes down to 5 or below, which happens here in upstate New York all too often. My gas bill was over $500 last month and I need to do something to reduce this. I have replaced nearly all of the windows with insulated vinyl and I've caulked and stuffed and caulked as many cracks and holes as I can.

My first step is to pipe a pry-sec loop system with OA reset and put a circulator pump on each of the 4 zones.

My next step is the boiler; I really like the weil-mclain ultra 230 but most professionals I talk to are telling me not to get it. I have read through a lot of threads on this site as well as others and have found mixed opinions on these boilers. It seems most people don’t like them due to cost. Others seem to think that they are not as efficient as advertised. I would like to know why people think they can’t make their 94% AFUE at temps over 140. All of their literature claims that they are 94% at regular temps and up to 98% at low temps. When you pay $500 a month for gas, every Btu you can get from your boiler counts.

Another suggestion I got was to put in a copper fin laars boiler with a 2 stage gas valve. This solution however will only deliver an 82% AFUE.

Am I wrong in thinking that with an 80% boiler, for every dollar I spend on gas 20cents goes up the flue, & with a 94% boiler only 6 cent goes up the flue?

Any suggestions would be appreciated especially from people that own these units

[cde72]

You have to remember with boilers, AFUE is relative... For an example, when the boiler starts up cold, 94% of each dollar of heat is going into the water, that is then being circulated through home, eventually heating it, however, once the boiler is hot, or once hot water returns to the boiler, less heat can be transfered from the burner to the water, so you start sending more heat up the flue, as well as money, with an 80% boiler, your heating water and not losing efficiency as it runs... I'm sure somebody else here will disagree... Personally I like boilers, but I really don't think the boiler is primary problem... If you do replace your boiler, I'd repipe the whole system... Most likely sediment has built up in the lines, trapping air pockets, and otherwise making your boiler worthless... Of course that is a very expensive plan...

[beenthere]

cde72 is right about disagreeing.

His AFUE explanation is wrong.

Afue takes into consideration warm up time, and standby loss.
Both an 80, and a 94% boiler are affected by it.

The ultra is modulating, and as the return water temp increases, it will modulate its input lower.
The 230 can go as low as 46,000 btu.

Ultra, Munchin, And Pinnical, are all expensive boilers, but can save you money, with their outdoor reset controls, and burner modulation. Will it save enough to justify the cost? Can't tell from here.

None of them are cure all boilers.

On a zoned system, their main advandage is that they aren't firing at full rate, when a small zone is calling for heat.

BUT, make sure if you get any of them, the company that installs it, knows how to install it properly, and knows how to service them.

[maccardi]

I see in all the piping drawings in wm manual as well as most other hi eff boilers that the secondary loop is not closed. Why is that? My idea of a pri-sec loop is to have the boiler inject the water into the loop with tee's less than 12" apart and for each zone to extract the water the same way. All of the manuals seem to show the zone as part of a manifold not giving the water a full loop when the zones are not calling.

One of my issues is recovery time when a zone calls for heat. this is the scenario: when a zone calls, the boiler starts heating the water from whatever the temp is to 180, if a second zone calls, it drops the temp and the boiler keeps running to try and make up the heat, and so on. Meanwhile I'm only running 140 or 150 degree water into my radiation and not getting enough heat to make set pt.

My theory is that these low mas boilers can heat the water faster allowing the radiation to produce more heat. Is this foolish thinking? If the house cools down on a really cold day the boiler can not raise the temp. I usually run a kerosene heater to help it along.

[johnsp]

Have you done a heat lose calc on this house? It's big, old, with probabaly little insulation and in a cold climate. 100K doesn't sound like enough. You're system should almost be running constantly since the thermostat doesn't get satisfied. You might need more radiantion in some parts of the house or as you are doing, get better head pressure on the zones and move more water. If you don't go with a modulating burner then a buffer tank would help in preventing short cycling and help balance multiple zones comming on at once.

[maccardi]

I haven’t done a technical heat loss but I figured 35 Btu’s per square foot and 600 Btu’s per foot radiation. Using these calcs, there is enough radiation on the site. These are probably the same figures that the original contractor used since it matches exactly. The boiler is probably undersized by about 30kbtu's. I’m certain that the 230K wm ultra would be oversized but with modulation it shouldn’t matter since it will throttle down once it makes the return temp set point. It also gives me the extra cushion I need if I add more baseboards. My biggest concern is getting the radiation at 180 or higher as quick as possible and maintaining it through the cycle. The existing boiler is not that old, 4 years. It was a replacement from buderus since the previous one had a cracked heat exchanger and failed before the warranty expired. The entire system is only about 18 years old.

[beenthere]

Your baseboard 600 btu rating is 4 gpm, make sure you are actually getting that, before you condemn your curent boiler.
I took it for granite that 100k was the IBR rating of your boiler, not the the input, or DOE.(oops)

Do the load calc, and check each loop length, to make sure you are getting proper flow.

Follow the manufacturers piping diagram and you won't be disappointed.

[drumn91]

Go with the Weil McLain..reputation and parts availability are key.

[simpleman]

Thats asking alot,I have never seen any emitter maintain
180 degree its not possible.Unless you dont plan on transfering any btus.How about a zone damper on the baseboard to stop the air current going across the emitter
till the water come up to 180.Just kidding.

I was always taught that you only need a 180 degree water on the coldest day of the year and depending on where you live,may only be a couple weeks out of the year.

Your problem could be where your btus get off at first.
Or as you mention under size boiler,which again to me is not a bad thing unless you are at the coldest day of the year all winter.

[maccardi]

Does anyone have any comments on the Pri-sec loop piping outlined in the boiler manuals? As I mentioned before, I would prefer to have the Pri loop closed and always moving flow. All of the low mass boiler diagrams show a manifold configuration.

My thinking is that you tee off the primary loop with the tee's less than 12" apart and run the pri loop gpm at say 20 then you pump off the pri loop into each zone at 10 gpm so your theoretically only taking half of the water wich should keep the return water drop to a minimum. If that description makes any sense.

[beenthere]

It should be piped as per the manual.
The ultra's control modual, will regulate firing rate based on the return temp, and responed quicker to zones opening and closing this way.

I have apartment buildings piped this way, and the ultra's respond very quikly piped this way.

Piping the way you suggest could would cause the boiler to short cycle, and that isn't what you want on any boiler, let alone a modulating boiler.

[simpleman]

Maccardi...I'm assume you want to pipe it pri/sec because
you want to use several different circulator and you dont
want the big one to over power the smaller circ?

Why do you want to keep return temps up on a condensing boiler?

If you are thinking going this route will give you some advantage when it get cold outside,to help the problem you
are having now,then I must said you're sadly mistaken.

Please share what it is you hope to accomplish?

I dont think he's listening Beenthere!

[beenthere]

I think he's been mislead by someone, or misread some article.

[maccardi]

I guess I never really thought thru the pri-sec piping with the condensing boiler. However it would still work with a conventional boiler using OA reset. You make a good point, thanks for bringing it up.

I am still concerned now with scale buildup in the pipes. What would be an easy way of determining and or fixing this short of replacing all of the piping?

Another question: Do Taco pumps get weak with age or just flat out fail?

I guess my real reason for starting this thread is to have someone experienced with the ultra's either talk me into it or out of it. Did anyone ever get an email address of md-mountain man that posted a similar thread back in Oct. 04? I would love to here how he has been doing with his ultra to date. Regardless of which boiler I choose there will be no cost to me, so that should negate the money argument. And yes, it will be furnished from a reputable distributor with a full warranty.

[tb7025]

I am also worried that a contractor oversized my ultra by placing a 230 in my house. Should I worry about it though since it will regulate the fire rate for the return temp. of the water?

[casturbo]

Originally posted by maccardi



Another question: Do Taco pumps get weak with age or just flat out fail?

The Taco circulator is the industry standard for quality and durability. Their failures I've noticed is from failed capacitors, debris jamming the impeller, wrong installation, running low on water pressure (cavitation, overheating) and finally wearing out. They appear to put out 100% capacity until they just one day stop working.

[joe22]

hey check out system 2000 boilers.......very nice system2000.com

[beenthere]

Originally posted by tb7025
I am also worried that a contractor oversized my ultra by placing a 230 in my house. Should I worry about it though since it will regulate the fire rate for the return temp. of the water?

Did your contractor install the outdoor sesor?

If he did you shouldn't have any trouble, unless you have a zone that is less then 20,000btu.
It will tend to short cycle then.
The draw back of the Ultra series is that it jumps from 155,000 to 230,000, they have no 199,000 boiler.

If you do have a small zone, the Ultra can have additional programimg done to prevent ezcessive short cycling. It can be programed for a wider deadband between burner off temp, and on. And the reset curve can be adjusted also.

BUT, the whole system has to be taken into consideratipn before any changes are made.

[tb7025]

Thanks for the info. That works out great since all my zones need more then 20,000 btu's

[brian in mass]

If $$ isn't an issue, then why not go with a Veissman ?