Dunkirk XEB - the good, the bad, the ugly

Upchucked

My wife and I have a home in the Hudson Valley of NY, but live in South Carolina at this time. We have finally decided to sell the house and have a very interested party and will probably go to contract shortly. As we don't use the house during the winter, we have both the heating system and the domestic water winterized. Last week, while our plumber was doing the job, he remarked that we need to address the heating system. He remarked that it is very old, and not very efficient. We have decided to install a new heating system as part of our offer, and will pay for it without asking the buyer for any part.

We have had four quotes on putting in a new heating system.

#1 was for removal of all the existing system, tank and oil and replacement with a Burnham ESC5 boiler. His quote noted "swap out & upsize to 2-420. This was the most expensive of the quotes.
#2 would remove all of the current heating system, the above ground tank and all the existing oil. He would then install an IBC LP system, model DC 33-124. Again new thermostat, 2 zones one zone of on-demand domestic hot water.
#3 would replace our old boiler with a new Burnam oil fired system, rated at 87% efficiency, completely repipe the system and includes a new digital thermostat, and a second zone. This was the same contractor as in #2, but this was about 20% cheaper than the IBC system.
#4 was for removal of everything, and installation of a Dunkirk XEB LP system with all plumbing and electrical work. This was the least expensive system, and was less than 50% of #1.

Our initial thought was to go with #4, but I know nothing about Dunkirk boilers and certainly don't want to stick the new buyer with a problem unit. This contractor has been in business for 68 years, the grandson of the original founder now runs the company, which carries his last name. He has a good reputation in the area and is signed up with all the usual suspects from Angie's List to Home Advisor. He is rated A+ by the BBB, but is not a member.

Thoughts? Is this boiler likely to be a problem for the new buyer? We like the idea of propane, if only to be rid of the mess that accompanies every oil buyer in existence.

Your response is most appreciated.

kcopp

no pricing please.... as stated at the top of the page??

JUGHNE

As said no pricing is to be shown.

Why do you want to change the system if you have a buyer for the house as is?
IIWM and if there was any deals to be made to drop your price, as a negotiating tool I would offer a boiler allowance of roughly the average of the 2 lower quotes.
You don't know what new owner would want, you could give them the quotes and offer some price drop. You have done a lot of the work for them already in getting prices.

Your new install could go south within a year for whatever reason and your new owner could be calling about lack of disclosure of problems. Also,some people are scared to death of LP.
If new buyers pick the contractor then the ball is in their court.
They may just keep the cash and not change the system.....an attractive offer to some people.

This allowance empowers the buyer and they may feel they get to decide.......they may not choose wisely....but they get to choose.
IMO

Upchucked

I don't operate in that manner. I won't sell a house to anyone with a boiler that I feel is unsatisfactory. I would put in the new system if I were keeping the house, and I won't do less for someone thinking of buying my house. The house is part of a 15 unit cooperative that extends over slightly less than 9 acres. 3 of the 15 units have never been built and are owned by family members of the 12 who have built. The co-op was formed in the early 1900's and my wife and I have been there for more than 30 years, and yet we are the 'newcomers'. This is not the type of place that people buy and sell with any regularity. Most of the current owners inherited their shares from parents or grandparents. We are selling and have agreed with the buyer for owner financing for 75% of the purchase price, payable over 20 years. We have insisted that they have a full engineering inspection prior to closing, with the understanding that if anything is not to their liking, they can withdraw without penalty. In getting the house ready for sale, we painted the entire house, put on a new roof for about 1/2 of the house, put in a new dishwasher, put in a new clothes dryer for one that wasn't working well, replaced the wood floors in two rooms where it was worn, and replaced a number of windows that weren't in the best of condition. We did this, not because the buyers ask, which they didn't, but because it was the right thing to do. The people who live in this area are our friends and I would hate to have them think we sold and took advantage of the buyers.

Sorry about mentioning the pricing of they systems, but I thought it best to put in what I had in order to fully explain. I have removed the prices, and relisted them in order of cost, from most to least. I hope that is acceptable, as I don't see how you can evaluate the offers without some idea as to cost.

kcopp

how many bathrooms/ showers do you have?
The IBC is a combi boiler.
Great unit imo but 2 showers at the same time is a stretch.
Dunkirk is nothing special. ok but mid efficiency at best.
Hard to say what is best as we don't know the house all that well.
Why would you need to completely re-pipe the system?
What is the radiation like there?

HVACNUT

Years ago I acquired from a neighbor a '69 Chevy Malibu, with a 350ci engine and 2 barrel carb. Somehow it came badged as a SS Chevelle from the factory.
When it was time to sell, I thought of removing the SS badges, but the buyer said "take $100 off the price and we've got a deal".
Ultimately, I dropped in a 454 with a Holley double pumper, Hurst shifter and a 4.11 rear with posi.
And still accepted $100 less than asking.

Upchucked

kcopp said:

how many bathrooms/ showers do you have?
The IBC is a combi boiler.
Great unit imo but 2 showers at the same time is a stretch.
Dunkirk is nothing special. ok but mid efficiency at best.
Hard to say what is best as we don't know the house all that well.
Why would you need to completely re-pipe the system?
What is the radiation like there?

The house sits on the edge of a lake in northern Dutchess County. It is built into the side of a hill, so the first floor is smaller than the second floor. The first floor contains the living room, dining room, a small office, kitchen, tv room and a full bath which also holds the washing machine and dryer. The furnace room is on the first floor, but reached by a separate entrance off the porch. Upstairs are four bedrooms and another bath and 1/2. One bedroom has a loft and another is arranged as an apartment with a small sitting room and ensuite with the 1/2 bath. The total square footage is around 1900.
The house was originally built in the late 1930's or early 1940'. The man who built the house was a plumber and much of what he put in was made of scraps he had as leftovers and he took some shortcuts that only he could explain. The next owner was his son, an electrician, who did the original wiring for the house. He added to it, but when we bought the house from his widow, not one electrician could understand what he had done. One of the electricians that I consulted was the part-time county electrical inspector, and he wanted to use the house to show people how NOT to wire a house. We fixed everything electrical, but only addressed plumbing issues as they came up. We never really did anything with the heating system and I suspect this guy wants to make sure it works the way it should.
I appreciate the comment about the Dunkirk. Efficiency isn't the most important issue. If the house was going to be used year round, as we did for many years, I would be more concerned. As it looks as though it will be seasonal, mostly in the summer months, the most important concerns are reliability and dependability. I want to be sure that it works without needing constant repairs and that it won't quit when needed the most.

Upchucked

HVACNUT said:

Years ago I acquired from a neighbor a '69 Chevy Malibu, with a 350ci engine and 2 barrel carb. Somehow it came badged as a SS Chevelle from the factory.

When it was time to sell, I thought of removing the SS badges, but the buyer said "take $100 off the price and we've got a deal".

Ultimately, I dropped in a 454 with a Holley double pumper, Hurst shifter and a 4.11 rear with posi.

And still accepted $100 less than asking.

I don't understand the point of your response, but I am guessing that you believe it unwise of me to put in items not requested by the seller. That may be the case, but I sleep very well at night and never have to make excuses for my actions. I won't sell anything to anyone that isn't working or as expected. It isn't in my nature.

Ironman

What type of emitters (radiators) do you have?

Does the present system heat all areas of the house sufficiently? If so, why does it need re-piping?

In order to help, we need more specifics. Can you post some pics of the present boiler and its near piping? Also of one of your emitters.

There's a WHOLE lot more to choosing which offere to accept than just a particular brand of boiler. Much of it depends upon the type of system that you have and the cost of different fuels in your area.

The biggest factor in the equation is the contractor, not the brand of boiler. Do your homework on the contractor. Get references and pics from jobs/customers he's done.

Zman

I absolutely applaud your honesty and transparency in this transaction. Why not take it up one more notch and ask the buyer what they would like? They are the ones that will have to pay the fuel bill and maintain the system.

KC_Jones

Which one of the quotes has done or has suggested a heatloss calculation to properly size the boiler?
An ESC5 for 1900 sq ft is 47 BTU's per sq ft. Unless you plan on heating with the windows open I would suggest that is most likely over sized.
That heat loss would be higher than my none insulated 100+ year old house.
If you stick with oil you are more limited in boiler size as they only go so small, but most likely you would be looking at the smallest one you can get.

Again it's all about the contractor.

Upchucked

They are generic baseboard hot water heating units. The same are used throughout the house.
I can't send you a photo, as I am 1,000 miles from the house, but I can tell you that the piping around the boiler looks like 6 pounds of cooked spaghetti..... I once tried to follow the inflow and outflow and gave up. Too many pipes, valve and turns to be able to figure it out. I think the re-piping was included to straighten out the mess and make it easier to service. As this was included in his quote, I have no issue with it.
As to the contractor, he is well known in the area, although his main office is 20 miles or more from the house. The company was started by his grandfather almost 70 years ago. It passed from Grandfather to Father to the current owner and has never had anyone running the company except someone with the same last name. They have a very high rating on every rating website I could find, have an A+ rating from the BBB and have no reported complaints. The owner answered the phone when we called and has responded to every question that I have posed in a timely and professional manner. Of everything involved in this project, I am most comfortable with my selection of him as a contractor, if that is our ultimate choice.
This morning, he responded to me that he thinks we will need a larger propane tank (which was switched to a smaller unit two years ago by the propane company, without telling us.), but he said that is dependent upon the manner the house is used. If seasonal, it will be fine, but if the new owners decide to make it their principal home, it may be too small. He also added that he is planning on using the XEB-4 unit with 112 BTU/h, which is AFUE of 83%. This is consistent with the quotes we received from other vendors with different model boilers.
My biggest question was about Dunkirk as a manufacturer. He tells me that his company has used Dunkirk for many years, that it is manufactured and maintained in NY and that should he need a part that is not in his stockroom, it is only a matter of hours away.

Upchucked

Zman said:

I absolutely applaud your honesty and transparency in this transaction. Why not take it up one more notch and ask the buyer what they would like? They are the ones that will have to pay the fuel bill and maintain the system.

I have advised them that we are installing a new heating system, and that we are most likely changing over to Propane. I told them that I will insure that the warranty is in their name and have offered to share the quote with them and to offer them a reduction in the price of $1,000 more than the quote if they want to wait until after their purchase to do the work. My experience has been that every quote is, at best, a guess and many times the final cost exceeds the quote because of unseen or unknown problems. That is why I offered the extra $1,000. Once I have it all worked out and ready to proceed, it will be their call as to whether we do it or they wait until after closing. Going into the winter months, in Dutchess/Columbia County, NY, I have a concern about the existing heating unit. I certainly don't want there to be a problem that would result in frozen pipes, etc., so I would rather just have it installed now, but since I have given them the option, I will abide by their choice.

KC_Jones

Upchucked said:

If seasonal, it will be fine, but if the new owners decide to make it their principal home, it may be too small. He also added that he is planning on using the XEB-4 unit with 112 BTU/h, which is AFUE of 83%. This is consistent with the quotes we received from other vendors with different model boilers.

You may like him and he may be a nice guy, but I can promise you they aren't sizing the boiler correctly, not by a long shot.

That boiler would put you at 50 btu/sqft

A heat loss calculation must be done that is the only way to properly size the boiler. The btu/sqft is sort of a reality check to see if the size is even reasonable. You could be putting in a boiler that is quite possibly close to double the size you need.

You will pay extra for a bigger boiler that isn't needed and the new homeowner will pay for it with lowered efficiency and possible shortened equipment life due to it short cycling itself to death.

HVACNUT

> @Upchucked said:
> Years ago I acquired from a neighbor a '69 Chevy Malibu, with a 350ci engine and 2 barrel carb. Somehow it came badged as a SS Chevelle from the factory.
>
> When it was time to sell, I thought of removing the SS badges, but the buyer said "take $100 off the price and we've got a deal".
>
> Ultimately, I dropped in a 454 with a Holley double pumper, Hurst shifter and a 4.11 rear with posi.
>
> And still accepted $100 less than asking.
>
> I don't understand the point of your response, but I am guessing that you believe it unwise of me to put in items not requested by the seller. That may be the case, but I sleep very well at night and never have to make excuses for my actions. I won't sell anything to anyone that isn't working or as expected. It isn't in my nature.

The point of my stupid story is, where does it end?
Old roof, crab grass, oil stains in the garage, dishes don't come out sparkling clean?
How old is the cesspool?
Any large trees near the house that can uproot during a storm?
Any aluminum wiring in the house, or between the meter and the line splice?

Sorry I'm not a PC kind of guy.

You were told the boiler is old and inefficient, not unsafe. (Why did I just envision my in-laws?)

The plumber told you. You tell the broker. The broker tells the buyer, and you work it out. Full disclosure.

It's up to the potential buyer how they want to proceed. If he/she has concerns about the boiler via their home inspector, you can go from there to do what needs to be done in order to make both sides happy, and sleep well.

Upchucked

It is a small town. Our plumber has been our plumber for 30+ years and he takes care of our heating system whenever it needs to be winterized. If he says it needs to be replaced, we believe him. He doesn't sell or install heating systems, and has no dog in the fight, so his opinion very much a concern to us.
Where does it end? When the house is in the condition we would expect it to be if we were buying it. There is no broker involved. We listed our house on Zillow, and I created a website for it. We have had over 3,000 'hits' on the website, have responded to 100+ potential buyers, have shown the house more than 2 dozen times, have received 8 offers. As this is a co-op, the buyer must be approved by the 14 other members, and 4 have met with the group. One was rejected and three have been approved (which means they can buy our house or any other house that should come on the market within the next 5 years). Of those 3, we chose one buyer who we felt was the best fit for the house, the co-op, and the community. It wasn't the highest offer, nor was it an all cash offer, but one that we felt was the BEST offer. We have not yet sent them contracts, as we wanted to address several issues, which includes the heating system. That is the last thing on the list and we are about to finalize the agreement for that..... if I can get an answer to my initial question.....

Upchucked

KC_Jones said:

Upchucked said:

.....

You may like him and he may be a nice guy, but I can promise you they aren't sizing the boiler correctly, not by a long shot.

That boiler would put you at 50 btu/sqft

A heat loss calculation must be done that is the only way to properly size the boiler. The btu/sqft is sort of a reality check to see if the size is even reasonable. You could be putting in a boiler that is quite possibly close to double the size you need.

You will pay extra for a bigger boiler that isn't needed and the new homeowner will pay for it with lowered efficiency and possible shortened equipment life due to it short cycling itself to death.

Thank you. That is the first response that give me pause. I will speak with the contractor this afternoon. I know he was basing his quote on what is there now.

DanHolohan

Upchucked, you're a very interesting and honorable guy. May I ask how old you are?

Upchucked

Aw, shucks. I am a mere kid of 72 years, 8 months and 12 days...and, hopefully still counting.

Upchucked

KC_Jones said:

Upchucked said:

You may like him and he may be a nice guy, but I can promise you they aren't sizing the boiler correctly, not by a long shot.

That boiler would put you at 50 btu/sqft

A heat loss calculation must be done that is the only way to properly size the boiler. The btu/sqft is sort of a reality check to see if the size is even reasonable. You could be putting in a boiler that is quite possibly close to double the size you need.

You will pay extra for a bigger boiler that isn't needed and the new homeowner will pay for it with lowered efficiency and possible shortened equipment life due to it short cycling itself to death.

I checked with each of the companies and all did a heat loss calculation and all of the units are sized accordingly.... I checked with each quote and the boiler they recommended.

The existing unit is sized for 149 BTU/h, but all the quotes were for sizes smaller than that. The house sits on a lake and has numerous windows facing the lake. In fact the lower floor is almost all glass when looking at it from the lake. The second floor is larger than the first. It also has a much higher ceiling, 12 feet throughout, with 20 feet in the room with the loft.
With the often sub-zero temps and high winds in the area, the contractors all based their calculations on 112 BTU/h and one said that this was necessary for hot water recovery.
As I think you know, I am certainly not an expert in this area, but don't want to start questioning everything each of the contractors tells me. I'm just trying not to make a mistake here. BTW, how does 112BTU/hr for a 1900 sq. foot, two story house equal to 50 BTU/sq. ft.?

DanHolohan

Ah, a contemporary! I thought so. Well done, young man.

Ironman

How does 112k btu for a 1900 sq. ft. house equal 50 btus per sq. ft? It doesn't - it equals almost 59 btus per sq. ft.! (112,000 / 1900 = 58.94).

That size is probably twice the boiler you need.

I've been doing load calcs for over 35 years and I've never see one where it came to over 35 btus per sq. ft. Even on the leakiest old farm house with no insulation and bad windows.

Newer boilers are more efficient and put more of their heat into the water instead of up the chimney. A lot of old timers refuse to learn the technical side of the trade and are stuck on the "bigger is better" misconception. It's not better, it's worse!

Let me simply illustrate:
IF, again, a big IF, a house needed 100k btus to heat it, it only needs that much only the coldest night of the year or when it's 0* outside. When it's 35* outside, the same house would only need 1/2 of that or 50k btus. (If 100k btus was needed to to keep it 70* inside when it's 0* outside, then only 50k btus is needed to keep 70* inside when it's 35* outside).

That means that even a correctly sized boiler is over-sized 99% of the time, because it only gets to 0* outside 1% of the heating season. This why many new more efficient boilers modulate to match the actual load. But over-sizing will defeat that and cause the boiler to short cycle which will reduce its efficiency and life span.

Get a contractor who will do an actual scientific heat loss calculation based on ACCA Manual J or equivalent.

SlantFin has a free heat loss calculator that you can download and that's accurate if the proper data is entered.

But again, your results should come out below 35 btus per sq.ft. It's not unusual for new, well insulated homes to need 1/2 of that.

Oh, by the way: there's nothing wrong with Utica/Dunkirk. Their modulating/condensing boiler line is actually very good. Their cast iron boilers are fine, but nothing spectacular.

KC_Jones

The output on the boiler you listed is 94k, 94,000/1900=49.47

How did they do the heat loss? To do the heat loss they need to measure all the rooms and look at windows, doors, insulation, basically as much of the house construction as they can.

DanHolohan

Good advice here.

Upchucked

KC_Jones said:

The output on the boiler you listed is 94k, 94,000/1900=49.47

How did they do the heat loss? To do the heat loss they need to measure all the rooms and look at windows, doors, insulation, basically as much of the house construction as they can.

They measured all of the rooms, length x width x height. They measured all of the heating units (length), they measured all of the windows and doors. They asked me about the insulation in the house, (R-30 in ceilings and crawlspaces above heated rooms; R-19 walls; R-11 in walls between rooms.

Also, in speaking with the representative from Dunkirk, he informed me the unit is designed for houses where the maximum heat needed is 112 BTU/h and the minimum is 20 BTU/h and that the amount of heat released is determined by the thermostat. He rejected the statement that it was oversized for a 1900 sq. foot house, saying that as long as it was not required to provide more than 112 BTU/h for any prolonged period, it was fine for installation.

KC_Jones

I did a very rough entry into the slant fin heat loss calculator wild guessing room size based on your description and square footage. At first I made some assumptions with virtually no insulation and literally entire walls of low end windows. With these insulation numbers you just posted I am getting 60k BTU heat loss. Unless I physically go to your house and measure this is a rough number, but I did it to give you an idea how off the numbers you are getting are. You could be even lower than this.

If they did all that measuring and came up with a heatloss of 112k for a 1900 sq ft house, they need to either fix the broken tape measure or go back to elementary school math. No way is the heat loss that high.

From what I am seeing that boiler XEB-4 can not modulate so I am not sure what they mean by minimum 20? It runs at 112, 94 output that's it. To get a variable output you need a modulating condensing boiler. Of course they will say that, I could put that boiler into a shed and it will keep it warm, but would that make sense? They actually didn't answer the question of over sizing, the statement you typed simply says it isn't too small. Being too big (IMHO) is worse than being too small.

Here is the thing, put in whatever makes you happy. I would like you to keep this in mind, I nor anyone on this board wants your money. Everyone here is a volunteer that only wants the absolute best information put out there...remember the absolute best.

The contractors and manufacturer you are talking to want your money. You buy a bigger boiler everyone gets more money. The heat works you are happy you give them a good review and everyone is happy, BUT you will also never know how good it could be, how efficient it could be, how much more comfortable it could be.

You seem to have high standards judging by what you have written, don't start sacrificing those standards because of someone else's lack of standards or lack of knowledge.

Perhaps your contractor needs some help or education, send them here everyone is more than happy to help.

NY_Rob

Many of the Pro's here have stated time and again they have never seen a home with heatloss exceeding 30Btu/SqFt.... and some live in and service Alaska.
Many 2X4 stick built homes fall in the 15-20Btu/SqFt heatloss range.

Even if your home was somehow at 25Btu/SqFt hetloss, you'd only need 47,500 Btu's on the coldest day of the year. If your heatloss is on the high end of the average at 20Btu/Sq Ft that would only amount to 38,000Btu's on the coldest days.

Installing a non-modulating boiler that can't fire down, which has a output of 94,000Btu's is not only inefficient but potentially damaging to the equipment and possibly your chimney.

Slant/Fin has an app that you can use to estimate your heatloss without involving your contractor... give it a try:

http://www.slantfin.com/slantfin-heat-loss-calculator/

HVACNUT

@Upchucked
Although IMO, the thousands you'll spend (not invest) on a boiler for a stranger would be better spent on your favorite charity, a vacation or college fund for the grandkids (if any), donate to your religious institution, Vegas, etc

You came to this forum seeking advice, and got it from the best in the biz. Even Dan Holohan himself dropped a hint to listen to the pros here, yet it seems as though it's falling on deaf ears.

Your trying to do what you think is best for your own conscience and a potential buyer. But by installing a grossly oversized boiler, you are not helping, but providing a serious disservice to the new owner by way of short cycling (wear and tear, shortening the lifespan of the components) and LACK of efficiency.

You sound like a great guy, and your heart is in the right place, so if your going through with this, please listen to the advice from the pros here.

Good luck.

P.S. My favorite charity is HVACNUT wants a Gunite pool. All donations accepted.

Upchucked

Gentlemen, I don't know what to say. I have asked 4 separate contractors to offer estimates. They are not related, and are in 3 separate counties. All have been in business for more than 20 years. Each has visited the house and inspected the house and what is currently installed. I have explained to each of them that the boiler that is currently in the house was not installed by any contractor, but was salvaged from our house on Cape Cod during a renovation. We converted from oil to gas and as a result had a relatively new oil fired boiler and rather than simply dispose of it we chose to put it in our house in New York. It is most likely the wrong size and each has acknowledged this.
Our house that is the subject of my inquiry is a 70+ year old house that was remodeled about 35 years ago by a contractor who took many, many shortcuts. He was my wife's first husband and he cut every corner possible. My wife ended up with the house in the divorce and while we lived in the house for more than 20 years, it is now being sold.
Each contractor did their own calculations and did not rely upon any measurement given by me.
Contractor number 1 offered the following:
IBC model DC 25-125, with 2 zones.
Contractor number 2 offered the following:
Burnham ESC5 (which I find rated at 90,000 BTU) and made a reference to swap out and upsize to 2-420, but I can't find any explanation for that comment. It may mean a change in the tank size.
Contractor number 3 has offered the Dunkirk XEB-4, which he indicates is 112,000 BTU.

Now, unless each of these three contractors is incompetent or attempting to sell me something I don't need, I can't understand how they could all do the calculations and come up with the same number and everyone here says it is wrong. I looked at the Slantfin calculator but I can't figure out some of the inputs so it is really not helpful for me at this point.

I received a call from one of the contractors this afternoon, to discuss moving the propane tank and managed to get his computations..... he used two different methods and he calculated at 47,975 and 33,975. He has quoted on a combi boiler and mentioned that he felt the extra capacity was needed for the hot water. I then called the other contractor we are seriously considering and asked him for his calculations, explaining that a question has come up about the unit being over-sized...he also did the calculation two different ways, and said they were both around 55,000.

If there is anyone in the area of Dutchess-Columbia-Ulster County, NY who wants to take a look and give me a bid, I will be happy to have you do so. Absent that, I am going to be forced to take one of these 3 bids, and will just have to trust that they know what they are doing.

Canucker

Perhaps I'm not reading it properly but it looks like they actually know how to do heat loss calculations, just not sure why they want to double the size of your boiler based on them. There is enough "fluff" in the calculations that it isn't necessary. I believe @Mark Eatherton calculated 100000 btuh heat loss of his own home and installed a boiler half the size. According to him it keeps up at all times. He obviously wouldn't do that to a customer's home but it shows that there is some leeway.

HVACNUT

@Upchucked
Go to the top of the page.
Click "Find a contractor in my area".
Enter your zip code and a 50 mile radius.
Click search, and make some calls.

Boon

Upchucked said >>> he used two different methods and he calculated at 47,975 and 33,975. He has quoted on a combi boiler and mentioned that he felt the extra capacity [the 112 number] was needed for the hot water<quote>

I think this solves the mystery. The extra capacity is needed for the combination unit. For the non-combi boilers, it isn't necessary to upsize for domestic water load.

KC_Jones

Last time I checked 55,000 didn't equal 90,000 nor does it equal 112,000. Perhaps this is some crazy new math they are using?

They are telling you that you need a 55,000 BTU boiler, but they want to install a 90,000 BTU boiler or a 112,000btu boiler.

What is their explanation of this "logic"?

They are trying to sell you something you don't need, they presented the numbers to invalidate their own recommendations.

I would press them, they are seriously confused, or as I said send them here.

To be clear it looks like their numbers are correct and yet they are choosing to ignore them completely. This is beyond my ability to comprehend and I have 7 year old children so I am used to some nonesense.

Harvey Ramer

If you are looking at a boiler that does both space heating and DHW on-demand, you typically don't want to go less than a 150k btu/h boiler size. This will get you around 3 gpm of instantaneous DHW. It may, however, require a buffer tank on the space heating side to prevent the boiler from short cycling.

Now if you are putting in an indirect water heater or a completely seperate water heater, than the boiler should be sized to match the heat load of the house as closely as possible.

KC_Jones

Harvey Ramer said:

If you are looking at a boiler that does both space heating and DHW on-demand, you typically don't want to go less than a 150k btu/h boiler size. This will get you around 3 gpm of instantaneous DHW. It may, however, require a buffer tank on the space heating side to prevent the boiler from short cycling.



Now if you are putting in an indirect water heater or a completely seperate water heater, than the boiler should be sized to match the heat load of the house as closely as possible.

Not trying to beat anyone up, but I am trying to work out the logic of ever using a combi boiler given the sizing issue. Looking for education for myself and the OP.

Put in a buffer so it can kind of do it's primary job a little better, but sized to do it's secondary job better.

Or put in an indirect with everything sized properly, most likely no buffer tank and still have endless hot water.

What is the combi saving? Once you add in a buffer and required piping isn't it just as expensive? Isn't it taking up just as much space too?

Trying to break this down very simply for the OP. Am I close?

Also the Dunkirk XEB being proposed isn't a combi boiler unless I am missing something in the install manual, so it is simply over sized.

Upchucked

Not being a professional, I can't find a price for the units on the internet. I do know that the XEB-II series boilers come in 6 sizes, measured by MBH:

42
75
112
150
187
225

One site mentioned that the cost, presumably to the homeowner ran from $1,850 to $4,250. I found one site that listed the XEB-4, which also included a pump and something else that I didn't recognize for $2,260. So, if that is the case, then the cost savings of dropping from a -4 to a -1 would be somewhere in the neighborhood of $350-$400. Why would a contractor, who wants a service contract and says he stands behind his work, over size a unit? What is the benefit? Certainly $400 can't be that much of an incentive?

KC_Jones

Upchucked said:

Why would a contractor, who wants a service contract and says he stands behind his work, over size a unit? What is the benefit? Certainly $400 can't be that much of an incentive?

Because most of the public doesn't know any better and won't know any different to complain about anything. Basically the house is warm end of story.

People are completely unaware of what they aren't getting because no one is educating themselves about it. You came here and now you are learning the truth about things.

If he sizes it properly it will heat the house, if he goes bigger he knows it will heat the house. Bigger is better right?

In a perfect world the burner on the boiler (with a modulating condensing boiler) will come on at the beginning of the season and not shut off till the end. That is the peak of efficiency, the further away from that you get the less efficient you are. So as I said before you pay more now and pay more over the life and if the short cycling is bad enough it can shorten the equipment life so you pay again sooner than you need to.

No matter how you look at it over sizing is bad, no matter what that contractor is telling you.

Did they do a radiation survey? How many feet of baseboard? That will also tell another story because most of the time that is the limiting factor.

Let's pretend you have the proper amount of baseboard for the 55,000 btu heat loss of your house. If you put in a boiler capable of 94,000 btu's guess how much you can use? Exactly 55,000 btu's. If you put in a boiler capable of 150,000 but's guess how much you can use? Yep 55,000 btu's. Again there is zero benefit to up sizing as the system at max capacity would put out 55,000 btu's no matter what you put into it.

Again did they do the radiation survey and what are the numbers?

Upchucked

OK, thank you all. I have reached my saturation point. You don't have to post anymore, I am done.

Thank you all I really appreciate the effort.

DanHolohan

Thanks for getting great discussion going. We wish you the best!

HVACNUT

> @DanHolohan said:
> Thanks for getting great discussion going. We wish you the best!

Yes we do!
And I bet you can't wait to get back to South Carolina now.
Post back about the heat pump system there, and we'll discuss that too. Lol.