Recommendations for replacing a Lenox Series XEB-4 (GWB81121E)

ntonkin

This natural gas boiler is in our 2nd home which is in Rhinelander, Wisconsin is 20 years old. During the spring annual maintenance, the tech said it needs major repairs . We have always kept the thermostat set at 58 degrees when we were gone because we were advised that setting it lower would shorten the life of the boiler. Well, it seems to have had a short life anyway. I am going to replace it this fall myself and would like some recommendations on what I should replace it with. The house is ~900 sq ft, - one and 3/4 story, fairly well insulated (blown in cellulose) and is over 100 yrs old - - there is only one zone. The Lenox seems to have plenty of capacity as it heats the house up quite quickly and until now, it has presented no issue. I would prefer to have a boiler that I could set the thermostat at around 45 degrees when we are not there and that would have longer life.

Would appreciate any ideas

Jamie Hall

Do a heat loss calculation. That's your first step. That Lenox may indeed have plenty of capacity -- in fact, if may well be too big. But until you know what capacity you actually need, you won't know.

Second, what kind of radiation do you have In the house? Baseboard? Radiators? That makes a difference, too, not in terms of boiler capacity, but in terms of what temperature do you need to run the water at to heat the house -- and may rule out some types of boilers.

So far so good.

Now longevity. The temperature at which you keep the house has almost nothing to do with how long a boiler may -- or may not -- last. There are several factors in longevity. One is what your return water temperatures are like. Most conventional boilers simply do not last well if the return water temperatures are low -- low enough for condensation to take place. Condensing boilers can handle that, though. Second, a boiler run nearly continuously will last longer than one that doesn't -- which is one reason to select a boiler well matched to what you need in terms of heat. Another factor is water chemistry -- ideally you would fill the heating system with good quality water (and, in a vacation home in a cold climate, antifreeze) with corrosion protection and never have to add water again. Reality isn't that way, but the less water you add the better.

EdTheHeaterMan

Further observation on that topic. What are the Major Repairs? Boiler section leaking is major! Wires burners and controls are not major unless there are several items failing all at once. That can be caused by oversized equipment. The fact that you can take the building from 50 something to 70 something, in your words: "The Lenox seems to have plenty of capacity as it heats the house up quite quickly" indicates that you have more capacity than you really need.

when you are not recovering from an unoccupied to an occupied condition, the boiler will operate as a steady temperature within 1 or 2 degrees. The oversized boiler will short cycle. On a design load condition day like maybe near -5°F in January if your building needs 42,000 BTU per hour to maintain 70° inside. If you have a 125,000 BTU boiler @ 80% efficiency there will be near 100,000 BTU output which is over 2x more than you need. So in any given hour, the burners would run for less than 30 minutes. BUT it won't be on for 30 then off for 30.... more like on for 4 and off for 4 minutes. That means the start-up sequence will go on 7 or more times per hour. OR 180 times per day. OR 1000 times per season.

I believe that everyone here can agree that turning a switch on and off 1000 times a year will cause the switch to fail sooner than a switch that is turned on and off only one time a day. The more times you use it, the more it will have time to wear out and fail.

Furthermore. The heater is not at peak efficiency until it operates for a few minutes. So if it only operates for a few minutes at a time... it will not be as efficient as one that operates with less capacity for longer run time.

"Slow and steady wins the race."

So getting a boiler that is closer to the actual size you need, so it will only cycle less than 1/2 of the time, will benefit you. Rusted burners and corrosion in the steel or cast iron heat exchange surfaces of the boiler may be a result of oversizing. This result is the condensation of flue gasses in the boiler and vent connections near the boiler, and the entire vent system

We here would like to know the condition of the boiler and what constitutes "Major repairs" Let's address what went wrong with what you have to see if we can keep the same from happening to the replacement boiler in the future.

ntonkin

I'll do another Heat Loss calculation next week when I go down there. The house has baseboard slant/fin type radiators and a small cast iron radiator in the basement.

As I remember, it was a small leak on the boiler section but I will look at the inspection sheet when I am down there and report everything listed.

This boiler replaced a Weil McClain HE-4 boiler which I installed in the fall of 1989 when we bought the house. The HE-4 worked well until it was damaged when the basement flooded during exceptionally heavy rains in the summer of 2000.

SuperJ

Unfortunately most residential cast iron boilers don't have the low RWT protection they really need.

There are a variety of factors that contribute to the premature death of a boiler. You can kill it from the water side with poor water quality. You can kill it from the flame side with poor combustion setup, lack of maintenance and low rwt causing corrosive condensation. And you can kill it with cycling. Every heat cycle expands and contracts the metal you can only do this so many times before things start to deteriorate.

ntonkin

Well, I finally got a heat loss calculation done, or at least I think I have... first I tried to do the Wisconsin Uniform Dwelling Code Energy worksheet but found this somewhat confusing. I ended up using the Home heat loss calculator from "Build it Solar" which indicated a UA of 310 and a Design Loss of 24,456 BTU/hr. The Wisconsin worksheet seemed to indicate a UA of 271.3 but I wasn't very confident in my completing the procedures correctly.

The observations and options part of the Heating Company"s report is as follows: Summary: corrosion on piping, good amount of buildup below burners, corrosion forming on heat exchanger, back flow/pressure reducing valve leaking, antifreeze is turning acid.
Immediate repair: Replace temperature relief valve, back flow preventer and pressure reducing valve.

System restoration and enhancements: Aquastat, draft motor, add cleaner, flush system, add new antifreeze.

Then he states: May be time to think about a more efficient system.

The more I look at this, the more I think there is no immediate reason to replace the boiler. The immediate repair part I can do myself no problem. We pay these people $10/month to provide priority service (should we have a demanding issue) and to do an annual checkup on the boiler system. These are the people that installed the boiler 20 years ago when I was deployed with the military. The bill for doing the above was to be: $3,138
I figure I can buy a new boiler for that much. Even if I don't replace it now, I would like to decide on an optimal replacement boiler for the not too distant future.

I appreciate your advice.

unclejohn

What have they been doing for 20 years if there is "a good amount of build up below burners" . Should have been cleaned during inspections. Does the boiler sidewall vent, what is the draft motor for. I use or should say used to since I,m retired Buderus CG boilers for cast iron jobs.

ntonkin

Yes, it is vented out the side of the house right above the basement's stone wall. The boiler has an induced draft blower, according to the model number. I' not sure why he was suggesting it be replaced - - why would that need to be replaced? We have been paying the $10/month since the boiler was installed and have never had an issue; so basically we have been paying $120/year for an annual boiler servicing.

We have owned the house for 31 years and have it very well insulated. We tore off the old asbestos siding, put tyvek housewrap under a premium vinyl "shake" siding. Had it fully insulated with blown in cellulose. Removed the roof shingles and installed a premium galvalume metal roof. The house was built in 1906.
I've already figured out that the heat loss calculation of 24,456 BTU/hr is screwy for my 900 sq ft (1 3/4 story) house. We did all the measuring and tried to follow the worksheet but 24.5K BTU/hr is clearly not the right answer. I have never done a heat loss analysis before and clearly still don't know how to do one.

I don't remember how I determined that the Weil-McLain HE4 (with ~ 82K BTU/hr output) was a reasonably sized boiler to heat the house, but it seemed adequate for the first 10 years we owned it.

I can still remember leaving for my reserve drill at 0300 one Saturday morning in the mid 1990's and it was 42 degrees below zero. What I don't remember is my wife complaining that the house was too cold that night, so the old HE-4 was getting the job done.

According to the model number, the Lenox boiler they installed has a 112K BTU/hr output. That's 30K BTU/hr more than the Weil-McLain HE-4, if my math is right.

I guess I need to talk to the outfit that replaced a boiler that had no complaint of being undersized, with a boiler with 30K BTU/hr greater output.

What is your advise on a replacement boiler?

EdTheHeaterMan

Some plumbing and heating supply houses may have a person that can do a proper load calculation.

What you need to provide is a drawing of the floor plan of your home with measurements. This will give you the ceiling and floor sq foot. The insulation r-factor between the inside living space and the outdoor temperature. The attic space is not usually included in the heated space. So the insulation in the ceiling of the top floor is the same as the insulation in the attic floor. In some cases, the roof and the ceiling is the same when there is no attic as in a cathedral ceiling

Next, the floor may be a basement floor or the floor may be over an unconditioned crawl space. This makes a difference. The insulation under the floor (if any) will need to be known by the person processing the load calculation.

Then the hight of the outside walls is needed. Also, the type of siding and insulation. Next the windows and doors total sq ft. Are they single glass, insulated glass, are there storm windows?

This is what comprises the envelope that keeps the cold out and the heat in. We need the outside walls (4 sides), the top (Ceiling), and the bottom (Floors) of the box.

Finally, How leaky is the house? Can the air blow thru the cracks and crevices around the windows doors and corners of the home. This is called infiltration. So we usually use tight, loose, or average.

Tight... is new construction
Loose... is an uninsulated farmhouse from the early 1900s
Average... is a well-constructed home built between 1970 and 2000
There are degrees in between tight, average, and loose.
Another way to look at this is Air Changes Per Hour, but for your purposes, I would use average, and error on the side of caution if the insulation is not known. I used to remove an outlet or switch cover and use a crochet needle to see if I could pul any insulation from inside the wall,

With this information, any qualified to perform a load calculation will get you a proper boiler size.

I hope this helps
Ed

mattmia2

Another way to verify your heat loss calculation, though with the extreme setback will be more difficult, is to look at your fuel use. You probably would recalculate your heat loss with the indoor temp you are keeping it at, look at the degree days for the period you have a record of fuel usage, and compare it to the fuel usage your calculations predict.(If you will end up recovering from a setback when it is near your design temp, you will need a little extra to be able to recover in a reasonable period of time.)

ratio

You can also try the Slant/Fin app. It's not too hard to grasp, & captures enough detail that you aren't going to feel like you're just guessing.

You will have to guess about how leaky your house is, though. Or perform a blower-door test.

ntonkin

I tried to find a slant/fin calculator that works with a pc but it only does apps. I don't do apps or cell phones or smart phones or androids. Where I live there is no cell phone towner in range. I have no cell phone either.
I found a heat loss calculator from U.S. Boiler Company that gave a procedure as follows:
1. Measure the total length of all outside walls for the house. Calculate gross wall area by multiplying total length by height of the walls.
2. Measure the window and door area. Select proper H.M.
3. Record Net Wall Area=(gross wall area minus door and window area) select proper H.M.
4. Measure the ceiling area and select H.M.
5. Measure floor area and select H.M. ( H.M. of 4 used over unheated basement )
6. Multiply Floor area by ceiling height to obtain volume of home and select proper air change factor: 1.61 for Loose House – 1.07 for Average House – .81 for Tight House.
7. Add the results from steps #1 – 6 to get your home’s total heat loss.

I followed this carefully with all the measurements we made and the results were: 37,850 BTU/hr. This still seems too low, althought this calculator doesn't consider the basement, however I did include the basement in the air change volume factor. It is a 3/4 basement with large rubble rock walls and it is heated. The remainding 1/4 that is over a crawl space is open to the basement. I used an H.M. of 1.0 for the adj.factor as I consider the house tighter than average - - with the tyvex housewrap and half of the windows replaced with Anderson casements and the rest with new storms installed. The house is considerably better insulated and tighter than it was in the 1990's when I installed the HE4.

We rarely stay the night at this house in the winter and I would like to keep the thermostat at ~50 degrees when we are not there. The tech recommended we keep it no lower than 58 degrees with the current boiler -- which is starting to look like is more than twice the size we really need.

ntonkin

I found another calculator at www.loadcalc.net/load.php called "Whole House Load Calculator" and it includes the basement. Results indicate a 33,150 BTU total heating load. This is the third heat loss calculation strategy that has indicated below 40,000 BTU heat loss.
I have found a Lochinvar Knight KHB055N for $2890 and it's supposed to put out 51,000 BTU/hr. This is the smallest one Lochinvar makes, I think. Would this be too oversized?
I've come to the conclusion that my major error was initially over sizing when I bought the HE4.

ntonkin

Does anyone recommend Weil-McLain CGi-3-PIN - 51K BTU - 85.1% AFUE - Hot Water Gas Boiler - Power Vent?

mattmia2

Here is a thought for your current system. You have 2 issues working against you with the extreme setback.

1. The boiler is oversized and when it is heating the indoors to 50-55 f the load is significantly less than it would be heating to indoor design temp.
2. The return temps to the boiler are somewhat lower than they normally would be because of the lower room temp.

This means it likely runs short cycles and probably satisfies the t-stat before it really gets up to temp to evaporate all the condensate out of the boiler and the venting.

An idea I have is to get a separate t-stat, put it in parallel with the main stat and set it to the longest cycles you can, let the temp fluctuate several degrees when it is at the 50 degree setpoint. Use your current stat with a cycle rate set for comfort to control the boiler when you are occupying the space, but turn that stat off and let the stat with the long cycle setting take over when it is unoccupied. That will help the system get up to temp and condense less and reduce the wear associated with more cycles.

ntonkin

mattmia2,
Thank you, I think that may be the best option in the short run. The boiler I now have really isn't completely shot. I think the best alternative is to implement your idea for the coming winter and see how this goes. I'll do the immediate replacement items, flush and replace the antifreeze and then put parallel thermostats in as you directed. Then next summer maybe I'll install a smaller boiler in 45K BTU to 60K BTU range.

What do you think of the Bosh Greenstar KBR 16-3 boiler? Or do you think another brand/size would be better for my situation?