Sizing Boiler Using DOE Booklet 25 Years Ago - What Went Wrong?

StanKatz

My original 120K BTU gas boiler needed replacement (it was leaking). I used a booklet I think was distributed by Dept. of Energy. I calculated about 60000 BTU for 0 deg design outdoor temp. I also added up all the baseboard in the house. That was 111.5 ft. Using a Slant Fin chart for 170 deg baseboard, 550 BTU/hr gave about 61000 BTU/hr. Of course, 25 year old baseboard might be less. Still, 60000 BTU/hr heat loss still sounded good. I didn't know how to use the 1.4x oversize factor. I figured it meant multiply 60000 x 1.4. giving 84000 BTU/hr input. I wasn't going to go that low. I thought what I needed was a boiler with an IBR net of at least 60000 BTU to the baseboards. I found a Utica boiler with IBR net 72000, which was a 100K BTU unit. Trying to find a contractor to put in a smaller boiler was challenging. Three contractors came and went after they couldn't change my mind. I think all the contractors in my county bend their elbows at the same watering hole. That's why out of the next ten or so contractors I called afterwards, only one responded. That contractor actually quoted a 100K boiler. I think he knew what was going on, and was starving for business. The experience with the installation was not good. Anyway, the new boiler kept our bedroom at 62F when at 0-10 deg outdoors. Original boiler was 68F. The bedroom is the only room with 3 exterior walls. The rest of the house was also cooler than with the original boiler. The outlet temperature of the new boiler is 180F, same as the old boiler. Using my infrared thermometer on the zones, I noticed that the biggest zone in sq. ft. had a 30 deg drop from outlet to return. The internet had some old rules of thumb, one of which indicated a 20F drop is the goal. I took matters in my own hands, and replaced the Taco 007 that came with the Utica, with a Taco 0010. No change. I then replaced the original zone valve on the biggest zone with a full port Honeywell valve. Success, got the 20 deg. drop. Rest of house was warm enough except bedroom. The house has three zones, so I replaced the other two zone with full port, hoping it would help the bedroom. It didn't. That's because even with small port valves, the bedroom zone was able to maintain a 20F deg. drop. The three zones are simple loops. I believe the rooms closest to the boiler on the bedroom loop have too much baseboard since they get too hot. If about 4ft. of baseboard was moved from the near to boiler rooms, to the bedroom, it could get back to 68F at design temp. of old boiler. Do you agree? I think the old boiler, having a larger heat exchanger, delivered more BTU's to the baseboards while coasting after firing. That compensated for the wrong distribution of baseboard on the bedroom loop. I don't know if I know what I'm talking about. Help!

DCContrarian

I'm not reading anything that suggests your boiler is undersized. The symptom of undersizing would be the burner runs continuously and the water temperature never reaches the set point. It sounds like you're not having any trouble with hitting the set point.

The output of a radiator is determined by the water temperature, the water flow rate, and the duty cycle — how much time it is off and how much time it is on — of the thermostat. If you're not hitting the thermostat set point the thermostat should be on 100% of the time, it's worth checking.

From your description, where the system used to be able to maintain temperature and no longer does, it sounds like something happened to the water flow rate when the boiler was switched. The water temperature that the boiler is delivering seems to be fine.

If I'm understanding, you have three zones, and it's just one room on one zone that's not satisfactory. Tell us more about that zone. How many other rooms, how many feet of radiator in each room, and where is the thermostat?

LRCCBJ

You stated:

"I believe the rooms closest to the boiler on the bedroom loop have too much baseboard since they get too hot. If about 4ft. of baseboard was moved from the near to boiler rooms, to the bedroom, it could get back to 68F at design temp. of old boiler."

This tells that the supply currently goes the the "rooms closest to the boiler" FIRST and then flows to the bedroom LAST. Therefore, the bedroom only sees approx. 165F supply temp.

However, it appears from the baseboard sizing that you'd want the supply to go to the bedroom FIRST and then flows to the "rooms closest to the boiler". In fact, it might be entirely possible that the original boiler was setup in this manner and the contractor got the supply and return to that zone reversed.

I also agree that the boiler is not undersized provided it makes 180F when checked at 0F ambient with all three zones calling.

Mad Dog_2

Whew....Mad Dog

Hot_water_fan

Ha a lot here. You’re not undersized.

WMno57

Simple solution. On cold days, crank aquastat up to 190F. Done.

EBEBRATT-Ed

I have found some zone valves to be more restrictive than others. I had a bad experience in my own house after replacing the boiler and new installing valves (one for an indirect water heater) and the other for the heatng system. The heating zone was very sluggish to heat due to lack of flow Nothing had changed. I had a new boiler and the same heating system but it refused to heat well until I changed the zone valve to one with a higher Cv

hot_rod

If you feel the output has dropped, try a brush and vacum on all the fine tube. Unless carpet was added or something else blocking the airflow across the fin tube, output should not drop with age.

Any Y strainers or air purgers that could be partially plugged? Valves that are not fully opened?

If changing the zone valves and upping to a 0010 made some difference, you are fighting a flow restriction.

Nothing changed in the structure to cause the load to increase?

DCContrarian

@LRCCBJ: " In fact, it might be entirely possible that the original boiler was setup in this manner and the contractor got the supply and return to that zone reversed."

That sounds unlikely, but how about this theory: when the boiler was installed, supply and return for the whole system were switched. On two of the three zones it doesn't make a difference but on one it does.

Intplm.

@StanKatz

I would check your work by doing a "heat loss calculation", checking your work against the DOE handbook, and seeing what you come up with.

Taking another look at the insulation, type of windows, room size, amount of, and type of baseboard heat eliments along with the size of the boiler. Compare those numbers to the DOE and see where you land. Its worth a look.

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1801079#Comment_1801079

If you're going down that path, I'd recommend looking at historical fuel consumption vs. weather. It's going to be more accurate. As outlined in this article:

https://www.greenbuildingadvisor.com/article/replacing-a-furnace-or-boiler

StanKatz

The "cold" master bedroom is at the end of the bedrooms/bathrooms hallway. The house is an L ranch. One leg, the hallway leg, is bedrooms/bathrooms, and the other leg is the living room, dining room, kitchen, and den. The thermostat in the dining room never has a problem being satisfied. However the thermostat in the hallway leg, on 0-20F outside days, never gets satisfied with both 'stats set to 72F. In order to prevent the circulator from running 24/7, I increased the 'stat in the dining room to 74F thus helping to send more heat into the hallway leg. Given it's a ranch house, I guess the hallway 'stat can be bypassed, and let the dining room 'stat control the whole house. Good idea?

Intplm.

@DCContrarian This is an excellent thought as long as it applies to current conditions and if he wants to do the upgrades required. This is a very good idea.

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1801081#Comment_1801081

OK, this is good information. This definitely suggests that the boiler has enough capacity, the problem is that leg isn't putting out enough heat.

To get more heat out, you need one (or more) of:

• Higher flow
• Hotter water
• More radiators

Without being there it's hard to know which of the three is going to be simplest to do.

If it's true that with the old boiler this leg used to be fine, and now it's not, I would suspect that something happened to reduce the flow. The question is whether you can figure out what that something was, and undo it.

Is there just one circulator for the whole system? Was it replaced when the boiler was replaced? Is it possible the guy put it in backwards?

StanKatz

Circulator is properly installed. The Taco 0010 that I installed seemed to be the biggest circulator that should be used in a 2600sq.ft. private residence. In fact, I did decide to go back to the original BG100 circulator to see if that helped. It didn't. To reiterate, all zone valves are high Cv types. The loop temp. drop in the hallway loop is 20F deg. Doesn't that mean all the BTU's that can be dumped at gas valve shut off, in that zone, are being dumped? I still think that the temperature profile from gas valve opening up, to the next gas valve opening up is different for the 100k vs 120k boiler. I think the total BTU delivered is greater for 120k unit due to the larger heat exchanger holding more heat for longer. In fact a larger heat exchanger will permit a greater water flow rate to all zones.

EdTheHeaterMan

@StanKatz said: “Anyway, the new boiler kept our bedroom at 62F when at 0-10 deg outdoors. Original boiler was 68F”

I find this to be related to the “Problem Contractor” (The experience with the installation was not good.) that has little understanding about Hydronics, and just did what he was told.  He probably didn’t even read the instructions, but installed it the same he was taught by his father or whoever he worked for before he went out on his own.

@StanKatz said: “The rest of the house was also cooler than with the original boiler”

Same things above.  I think he needs more training, and your home was one of his on the job training experiences.  

@StanKatz said: “I then replaced the original zone valve on the biggest zone with a full port Honeywell valve. Success, got the 20 deg. drop. Rest of house was warm enough except bedroom” 

Now you learned something about water flow and selecting the proper zone valves for the job.  That larger port valve has a higher Cv. less restriction so the water can move faster.  That original zone valve reduced the flow from the normal 4 GPM in that 3/4" zone to 2.5 GPM.  that means the zone could only make 25,000 BTUh thru that valve.  With The larger port valve, you got that extra gallon per minute.  That means that you may get 10,000 more BTUh in that loop 

The other zones may only have 25,000 BTUh or less of radiator element, so allowing more water flow will not let more BTUh get to those radiators. You may have heard the expression “You can’t fit 10 pounds of potatoes into a five pound sack”.  That is what is happening on the other loops.  

@StanKatz said: “If about 4ft. of baseboard was moved from the near to boiler rooms, to the bedroom, it could get back to 68F at design temp. of old boiler. Do you agree?”

That is one way to look at it.  The other way is that the original incompetent installer may have inadvertently reversed the direction of flow to that sone (or all the zones for that matter) after removing the old boiler and piping up the new boiler.   

@StanKatz said: “I think the old boiler, having a larger heat exchanger, delivered more BTU's to the baseboards while coasting after firing”

This is unlikely.  The old boiler no matter how over sized it was, could only deliver the amount of heat that the radiators could accept.  Once the boiler heated up to the limit temperature, the High limit would shut off the burner and the pump would just force that temperature water to the radiators until those radiators could lower the boiler temperature to allow the burner to fire up again.  Then it would go off by the limit again, and so on, and so on,..

A home that can only deliver 70,000 BTUh from the radiators to the rooms, will only accept 70,000 BTUh from the boiler, no matter if it was a 72,000 BTU boiler or a 140,000 BTU boiler or a 210,000 BTU boiler.   The burner would just run 96% of the time on a 72,000 boiler and 50% of the time on the 140,000 BTU boiler and 33% of the time on a 210.000 BTU boiler .   The problem is that the larger 140,000 BTU oversized boiler will not run for 30 minutes on and 30 minutes off.  It will short cycle maybe 5 minutes on and 5 minutes off, once it reaches the limit temperature.   Not very efficient.   The 210,000 boiler burner will run for 3 minutes on and 9 minutes off.      

@StanKatz said: “The "cold" master bedroom is at the end of the bedrooms/bathrooms hallway”

Is this the 3 exterior wall room?  Then that room should have the thermostat in it.  If the thermostat is in the hallway, that may be the problem.  Most hallways do not have radiators in them.  Depending on heat from the bedrooms to satisfy the thermostat in the hall is not a great design.  And it gets even worse if all the bedroom doors are closed.  Just Sayin’

@StanKatz said: “In order to prevent the circulator from running 24/7, I increased the 'stat in the dining room to 74F thus helping to send more heat into the hallway leg.“

This makes no sense…  Only makes sense if the thermostat for the bedrooms is located in the hallway and when the dining room thermostat is set higher, that hotter dining room heat travels down the hall to satisfy the hall thermostat.   Can you tell me what the actual temperature in the different bedrooms is when the thermostat in the hall is set at 70° and the living room thermostat is set at 68°?

A floor plan with baseboard element length for each room, and the thermostat locations is the only way to diagnose this.  Otherwise we are all just guessing. 

You can always keep shooting the parts cannon until you get it right.  Larger circulator pump did nothing, two of the three zone valves did nothing, maybe you need a new thermostat that can measure the temperature in the problem zones better. Change the 4 feet of radiator from one end to the other,  Perhaps change the ¾” pipes to 1” pipe so you can get more heat to those problem radiators.  After you spend all that money on moving radiators and larger pipes and other stuff, perhaps vacuum cleaning the underside of the radiator elements will have some effect.  Another free adjustment is the 190° high limit setting.  But you should only do the inexpensive things after you have spent lots of money on the harder stuff first.

Hope this helps and the sarcasm is taken in jest as intended.

Mr. Ed.

EBEBRATT-Ed

Go back to the basics.

Check the gas input and do a combustion test. maybe the boiler was never set up properly. You can have a 100,000 btu boiler according to the nameplate that does not mean it is firing at that rate.

If it is firing correctly and the boiler is clean and does not heat the house then you have 1 of 2 problems. The heat isn't getting from the boiler to the radiation due to a restriction, flow or circulator problem or the house has more heat loss than the radiation can handle.

First check the heat loss of the house

then check the gas input and combustion

then check if the radiation meets or exceeds the house heat loss

If the above 3 thing check out you have a flow problem.

EdTheHeaterMan

A few other questions come to mind

• The old boiler was oversized by at least 20%. (120K) Was that the IBR net or the Input?
• The new boiler has a Net of 72K, so what was the input on that one? 100K ?
• How easy is it to reverse that one zone with the cold room?
• How easy is ti to draw a floor plan and indicate the thermostat locations and the radiator locations, and what zone thermostat each radiator is connected to? Can you post a photo of the drawing?

DCContrarian

"I still think that the temperature profile from gas valve opening up, to the next gas valve opening up is different for the 100k vs 120k boiler. I think the total BTU delivered is greater for 120k unit due to the larger heat exchanger holding more heat for longer. In fact a larger heat exchanger will permit a greater water flow rate to all zones."

All the radiators care about is water temperature and flow. A higher capacity boiler isn't going to have a higher water temperature at the same aquastat setting.

We've been focusing on water flow, but is it possible the old boiler just had a higher water temperature setting? Like the 190F that Ed suggests above? That would be the simplest fix.

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1801100#Comment_1801100

"I still think that the temperature profile from gas valve opening up, to the next gas valve opening up is different for the 100k vs 120k boiler. I think the total BTU delivered is greater for 120k unit due to the larger heat exchanger holding more heat for longer. In fact a larger heat exchanger will permit a greater water flow rate to all zones."

Remember in grade school when the teacher gave you a math problem, and they said "Show the work"? That is because guessing the correct answer or copying the correct answer from someone else didn't prove that you know how to get that answer. Same goes here. A BTU is a BTU is a BTU! and if your home loses 47,341 BTUs in any given hour at a particular outdoor temperature, then that is all the BTUs that the gas meter or oil burner will let in. That is because the limits or thermostats will turn off the BTU making device when there are more BTU than needed. The problem is the wasted BTUs from inefficient operation or short cycling.  

To keep that wasting from happening, you want to put the correct amount of BTUs into the home in the most efficient way.  So with your analogy of the 120 being better than the 100, then wouldn’t the 210 be better than the 100?  That 210 will certainly have more space to store those BTUs than the 120 that, by your definition, is better?  How much better is 120 over the 100 if the home only needs 80 or 90 or 72 or 61?.   

I did the math for the 210 and the 140 and the 72 based on a home that might only need 70.    The 72 is clearly the best choice because there will be much less burner off cycle loss out the vent.  How the 70 is distributed to the home is the important question, and @StanKatz mentioned that the contractor may not have been the best choice.  

We are only guessing without all the pertinent information.  That is why I requested the floor plan with the specifics of the thermostats and radiators.  Only with that information, short of an onsite inspection, will we be able to solve this problem.  

But you are correct with the 190° limit idea. Doing the less expensive adjustments are always better that spending money guessing. Who's to say the old boiler aquastat was not out of calibration by 10° and that simple adjustment fixes the problem without all the other work.

StanKatz

I have attached a hand drawn plan of my home with the baseboards labeled in feet. I'm an old dude, and can't handle pc drawing packages, so forgive me. There are little circles where the 'stats are. I found when remeasuring total feet of baseboard I got 128.5 ft. of baseboard. Using 540BTU per ft. of 170F deg. baseboard, I now have 69,390 BTU of radiation. Given an I-B-R of 72,000 BTU for my replacement boiler, it looks like my choice is a Goldilocks one.

I have also attached a photo of my boiler output piping. I noticed that the zone to the living room leg (the zone that has no problem reaching 'stat setpoint) has its own 3/4" pipe port off the main boiler outlet…but the basement and bedroom hallway zones are jammed into one 2 ft. length of 3/4" pipe, with a 90 degree angle, which then goes to a Y of two 3/4" pipes to the zones. I'm wondering if that is causing my problems? If so, then the problem is indeed inadequate flow rate. It's been this way since the house was built.

baseboard.pdf

EdTheHeaterMan

From this drawing, I assume that you have the zones set up like this. and as i suspected, the blue zone has the thermostat in the hallway, where there are no radiators from the zone that the thermostat is controlling. And based on your drawing, the heat from the kitchen will travel to the hallway and effect the temperature in the hallway. So my first fix would be to move the thermostat to the master bedroom.

I also believe that the master bedroom is the problem room because it is the only room in that zone that has 3 outside walls. Adding 4 feet of radiator to that room may be the right thing to do, but I would move the thermostat first because there is no plumbing work involved with that adjustment.  

Only after testing the new thermostat location and finding that did not solve the problem, would I add more radiator to that zone.  And since you need to remove the water to do that adjustment, I would redesign the near boiler piping at the same time like this.

See how the supply pipe is a full 1-1/4 as it leaves the boiler then changes to 1" for the living room/kitchen zone. then it splits to 3/4" to pick up each end of that zone. Somewhere in the center of that zone you will need to cut a 1 x 3/4 x 3/4 tee into that loop so you can return it to the boiler using 1". Or you can home run the 3/4" back to the boiler room. all the returns need to enter the common piping at 1-1/4" to return to the boiler room.

EdTheHeaterMan

The pipe sizing is a little overkill because the boiler does not need anything larger than 1" copper because the NET is less than 80,000 BTUh. and 1" copper can accommodate 80K. So you can reduce the 1-1/4" copper to 1" copper to keep cost down. I would not reduce the 1" shared pipe to the Living/Kitchen zone. Keep that 1" until you split off to do half of that zone on each branch of the 1 x 3/4 x 3/4 Tee.

StanKatz

What a gorgeous piping schematic! Sorry I didn't take a picture of the home run piping. It's already exactly as you have drawn it. Moving the thermostat to another hard wired one in the master bedroom will cost about $600 using an electrician in my New York Metro area. Is there such a thing as wireless thermostats? Although you didn't come right out and say it, it seems you don't think that jamming two zones into one piece of 2ft. 3/4" pipe before the Y is the root of the problem. Or, yes it's a problem, but lets see if we can live with the problem, by moving the thermostat. I could be looking at $1500 - $2000 charge by a plumber in my area to redo according to your schematic. Yes, let's see if we can live with the plumbing problem! BTW, as another poster suggested, I did consider moving the aquastat up to 190F. However, this year's heating bill was 20% higher than last year's! I'll just stick with 180F.

Hot_water_fan

1. Politics are not allowed.
   
2. Heating bills are rates x usage. How did your usage change? Usage is mostly weather driven, so colder winters will cost more all else equal. Often, someone here will bemoan a higher bill, blame it on the boiler, then it comes out that their fuel unit costs increased while usage stayed similar or even decreased.

StanKatz

I didn't know that voicing concerns over how government affects my utility bills in the US is political speech. My natural gas and electric usage is shown on bar graphs in my bills for each month. Eyeballing those bars I see that my usage for utilities was almost identical for '22 and '23 heating seasons. NYSERDA (a New York government agency) reported Heating Degree Days for New York State were 5190 in 2022 and 5189 in 2023.

StanKatz

Correction. the last post should be for heating seasons ending in 2023 and 2024.

Hot_water_fan

ha don’t shoot the messenger. It’s the rules.

Running 190F will use more energy than 180F, but not a significant amount. Cheaper than repiping or anything else.

MikeL_2

Almost all atmospheric residential boilers are oversized for all but the few days or weeks of design conditions. We couldn't find an oil fired atmospheric boiler that matched our exact heat loss when we installed a new boiler several years ago.

Our thermostat stays fixed at 62° during the day and sets back to 58° overnight. That's our comfort level. We're able to heat our home with 150° swt.

We've accomplished some room by room balancing using table top thermometers and the adjustable damper on our heat emitters. We made sure that the bottom air inlet area of all of the baseboard units is not blocked by carpet or other flooring. We've also removed the heat emitters front cover and carefully vacuumed the dander, dust, & pet hair from the finned tube.

EdTheHeaterMan

. @StanKatz said: What a gorgeous piping schematic! Sorry I didn't take a picture of the home run piping. It's already exactly as you have drawn it.

AND

. @StanKatz said: Although you didn't come right out and say it, it seems you don't think that jamming two zones into one piece of 2ft. 3/4" pipe before the Y is the root of the problem.

AND this Photo

seem to contradict each other.

I must say that this illustration on the left has very little resemblance to the illustration on the right.

The 1-1/4" riser at the boiler stops just after the 1/2" water feed line, the air scoop is not connected to remove air from all the zones, and the circulator pump is nowhere to be seen in your photograph.

The illustration on the right clearly shows the circulator pump pushing the water away from the expansion tank, that is connected directly under the air vent, that is on the common header pipe for all zones.  Also the common header pipe continues full 1-1/4 (or at least full 1" for your system) until all the branch zone supply tee fittings are at the end of the last branch zone (in the case of my diagram is the basement zone.)  So to answer your query: Are both the basement and the bedroom zones being JAMED into a single ¾” branch and divided into two additional ¾” branch zones? is not the best design.  It may work but that will depend on how much heat is required and how much heat can be delivered by a single ¾” pipe to the two zones if they both call for heat at the same time.

another important point is that the living room and kitchen zone is one continous loop in your system but in the digram on the right shows that zone to be divided somewhere in the middle so as to keep the total of element on any one 3/4" pipe to be less than 45 feet. As it stands now you have over 70 feet on a single loop.

In your original post you indicated that some of the living room zone loop may have lower temperature at the end of the run, but in your latest post you indicated that the living room zone has no problem. As for paying for a plumber to fix the poor design, I would venture to say that you make all the wet changes at the same time, in leu of fixing just the 2 pipes JAMED into one pipe problem. If you are going to the expense of draining the system to fix one pipe issue, or adding an additional 4 feet of radiator in the cold room, then to redesign the near boiler piping to make the system work better and eliminate air problems, at the same time, then that is money well spent.

If that system was poorly designed with the old boiler and it worked, then just do the thermostat move without any wet piping work to see if that solves the problem. YES, there are wireless thermostats, but you need to mess with batteries every year and that is another thing to go wrong. Bite the bullet and get a handyman (not an electrician) to run a thermostat wire. Thermostat wiring is not an item that needs a licensed electrician to pull a permit to make that change. It is your average DIY project or a handyman can make that happen with ease, in most cases.

If you end up getting to the wet piping repair/redesign, then you should read this. https://s3.amazonaws.com/s3.supplyhouse.com/product_files/108119-Reference%20Guide.pdf

it will make some of what I have said previously a little more clear. When I first got this booklet, I read it about 4 or 5 times. Each time another concept clicked. And it was written for the average guy, not the mechanical engineer. It is what I used as my textbook for the training classes I used to teach years ago.

MikeL_2

The near boiler piping shown is less than ideal.

Is the boiler located in the basement?

And if so, where in the basement? And what's its source of combustion air?

Do your tstats have adjustable anticipator settings?

EdTheHeaterMan

MikeL_2 said: The near boiler piping shown is less than ideal.

Agree

MikeL_2 said: Is the boiler located in the basement?

Looks like it but that should not matter in resolving the not enough heat issue

MikeL_2 said: And if so, where in the basement? And what's its source of combustion air?

Combustion air has little to do with the not enough heat issue that @StanKatz has presented. if there was a combustion air issue, wouldn't that manifest as a different problem? (Like sooting or other incomplete combustion issues.)

MikeL_2 said: Do your tstats have adjustable anticipator settings?

Now this makes more sense, if the Heat Anticipator on an old thermostat is connected to a Taco 570 type zone valve, you can get a short cycling problem that's associated with the thermostat. That would be something to look at, but IIRC the OP states he has Honeywell zone valves.

MikeL_2

I very respectfully disagree. Combustion air drawn in through drafty windows, poor weather stripping, cracks, crevices, attics, and other poorly sealed areas will cool the indoors & occupants on its way to the boiler; I've witnessed it scores of times..…

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1801269#Comment_1801269

But OP said it worked fine with the old boiler. Why would the combustion air path change?

DCContrarian

"Now this makes more sense, if the Heat Anticipator on an old thermostat is connected to a Taco 570 type zone valve, you can get a short cycling problem that's associated with the thermostat. That would be something to look at, but IIRC the OP states he has Honeywell zone valves."

OP said above circulator was running continuously.

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1801269#Comment_1801269

Good point, but would that not also be the case with the old boiler? I still don't see the connection of the combustion air to the lower temperature throughout the home based only on the boiler replacement. Then replacing the zone valve on the larger zone fixing the problem on that zone. but still having a low temperature on one room on a different zone. I believe that the combustion air thru drafty windows on the occupied floor when the boiler is in a basement has more to do with total home efficiency and less to do with this particular problem.

BUT LETS PUT IT OUT THERE:

HAY @StanKatz, Did you replace any windows lately?

StanKatz

I apologize for not providing more photos of the basement boiler. Please see attached. As for combustion air, the boiler is indeed getting it from openings mostly behind finished basement paneling I can't get to. The boiler is in the unfinished part, and I spent effort to seal that part. I know there's plenty of air since the house pulls 2000 cu ft/min through a blower door. The motorized damper dumps so much heat into the basement during shutdown cycle that it is always uncomfortably warm in the unfinished basement at times of the coldest part of the winter. Therefore, it seems to me the boiler is drawing in warm air, not cold. Thanks for the "Zoning Made Easy", I have a copy from years ago, and it's a wonderful reference.

StanKatz

The 'tstats have resistor wire anticipators set to the zoning valve amps.

StanKatz

The upstairs living area level, is very well sealed. With the basement door closed, the boiler's main source of air has to come from the basement area left unsealed. There are no drafts upstairs when the boiler is on.

StanKatz

The house still has its 50 year old wood Anderson windows. They have been maintained and to this day are as tight as the day they were made. Great windows!

MaxMercy

That's your new boiler??