Hot Water Boiler Burning Way Too Much Gas

Tuto0174_

I need help EXPERTS:

I have a pretty old peerless hot water boiler (Baseboard heating),  165,000 BTU. My house was built in 1950, 2 family, it's an old house. The area to be heated is 1,700 sqf, it's small (First floor and basement). My issue is that I am paying close to $300 monthly during the cold months, this is extremely high compared to most other properties. Some experts have told me that my boiler is oversized, while some say it doesn't really matter what size the boiler is. 

I admit that the insulation in my house is not ideal, but to pay that much money in gas, something has to be very wrong. The boiler is used to heat the 1st apartment and basement (finished). It seems like years ago this boiler was used to heat up the whole house as the second apartment has baseboards but now uses forced air heat. I bought this house 3 years ago, it is in NJ.

 Should I look into changing my boiler to  a more efficient/ better sized? What would be an appropriate BTU for 1700 sqf area? 

Jamie Hall

Two things you can do fairly quickly -- and you'll need one of them for any future plans anyway. That one is to determine the heat loss of the structure. There are a number of on-line programs which can help you thought this. I prefer this one: https://www.slantfin.com/slantfin-heat-loss-calculator/ but there are others.

In relation to that, it will help you see where you can make improvements -- better insulation, repairing windows and providing storm windows, etc. -- which will be the best possible investment you can make in reducing heat loss -- and therefore fuel costs.

On the boiler, the best thing you can do is to find a competent heating tech -- there are several we know o in your area -- who will come and perform the necessary tests and cleaning and adjustments needed to have your boiler perform at its best. This should be done annually, anyway.

mattmia2

There are definitely a few things that should be tidied up with that boiler besides cleaning and adjustment. It may also be set up as warm start, especially if it is oversized, that could have a significant effect on efficiency.

rick in Alaska

How many btu's is that boiler? With 10 tubes, I am guessing 300,00?? Even with a horrible insulation job, it would still be under 100,000 for your load, which would make that boiler grossly oversized.
Rick

EBEBRATT-Ed

With the second floor having it's own heating system you have no ceiling heat loss. Your boiler is very much over sized.

I don't know your gas rates but your bill does sound a little high

Is the boiler on a separate gas meter? Any other gas appliances on that meter? I see a water heater in the picture. Is the second floor furnace on a different meter. Make sure when the second? meter was installed and they split the gas piping that there range, water heater, gas dryer are not on your meter

Check "find a contractor" on this site and get a competent technician. Maybe @clammy or @EzzyT will respond

Tuto0174_

Thank you all for your answers. The gas meter on this boiler is separated from the second floor furnace. When this baby is turned off, during the summer, my Bill is 35 bucks per month, while during the winter, it is around $300..... We actually have storm windows and insulation in some but not all walls, the siding is made from stucco (Not sure if this helps with insulation).

Some contractor told me that this boiler was once a steam boiler and has been converted to hot water. We had a radiator (not working at the time) at the entrance of the house when I bought the house, inside the apartment and basement all new baseboards. Perhaps, this boiler was altered. For what I read on the label, this boiler has 165,000 btus, but I am not sure if it'saccurate. I would like to add that the damper is not working, it remains open the whole time. 

I forgot to add, when I bought the house the boilers temperature was set to 200 or 220. Recently, while doing maintenance with a new company, the tech lowered the temp to 180. Now with this new temperature, when it's too cold outside, the temperature in the house struggles to reach 70 degrees. If it's so oversized, why it can't keep up with such a small area?... This boiler is such a pain in the butt but at least it's working and keeping us warm but we are paying big bucks for it lol.

kcopp

I would get an energy audit done... Thats a blower door test and insulation assessment. The fact that the house needs 200F water to keep you warm when the temps plummet says that the house is drafty and needs more insulation. A new boiler may or may not help. If the heat you produce heads up and outside makes little difference.

SuperTech

Make sure that the baseboards don't have any obstructions that will decrease airflow through them. No furniture in front of them, no carpet blocking the bottom and make sure all the fins are clean. The covers need to be removed and the fins vacuumed out every once in while. I've seen a few houses that would struggle unless the high limit was turned up to 200 degrees. After vacuuming the baseboards and moving some furniture away from them the house would heat with 180 degree water without any problems. I believe most fin tube baseboards are designed for 180 degree water. Some homes can heat with much lower temperature water.

clammy

If your in jersey I would say it’s not uncommon moons ago to convert a steam to hot water anything to save the Ho a buck in the short run and let them pay w no rio . .was it right no but a lot of guys see a boiler as a boiler and back then would just convert instead of install the proper boiler espically if it was a old dinosaur .the high aquastat temp may have been set up because they couldn’t fit enough baseboard or didn’t install enough and most likely no heat lose was done very common years ago , so they turned up the aquastat when it didn’t meet the heat lose simple as that . Using a converted steam boiler as a hot water is silly . The boiler steam passes are larger and not designed for the purpose of heat water it purpose is to make steam a converted steam will not operate as efficientas a hot water boiler . To boot at 165000 btu is enough to do a 3000 sq ft home easily . So your way over sized . You need a heat lose and a evaluation of the heating convectors to see if they meet design day . If not more baseboard will be needed to be installed and what ever else would need to need corrected . I would also recommend a good flushing of the system . Peace and good luck clammy

HomerJSmith

The reason that the water temp was at 200-220 deg was that a lower temp would not overcome the btu loss thru the house envelope on the coldest day in winter, as you already know. You don't have enough heat emitters in the house to operate the boiler at a lower temp. If you had more heat emitters you could put more btu's into the house at a lower boiler temp.

Ya, 10 tubes which I would think is about 20-25,000 btu's per tube. You can produce the heat energy, you just can't get it where you want it. What is the supply temp and the return temp? Probably, a tight differential. Does the boiler cycle all the time or does it not cycle at all?

The boiler has to match the heat emitters and the heat emitters must match the btu loss or inefficiencies happen. For 1700 sq ft, your boiler is way oversized, I'd say.

The two things that have to do with heat energy transfer sys are flow and temperature.

Tuto0174_

The boile runs in cycles. 1st apartment has 6 rooms and 6 baseboards, one in each room, while basement has 4 baseboards and 4 rooms. 

Please see additional pictures of the boiler. If I get a new boiler with 88k btus, will that be suffient for my 1700 sqf living space?

Jamie Hall

The only correct way to size a new boiler for hot water heat is to do a heat loss calculation on the building. Every building is different, and there are no shortcuts. Fortunately, heat loss calculations are not at all dificult. Slant/Fin has a nice calculator here: https://www.slantfin.com/slantfin-heat-loss-calculator/

GW

If you’re more interested in lowering heating costs than buying a new boiler (which would likely save some fuel) I’d recommend looking for more basic things like fresh air entering the basement level. 

Find a means to make smoke (which is a pain if you’re not a smoker!) and start puffing. You’re getting cold air in somewhere. 

Do you have icicles or ice dams on the roof? What comes in must go out. (In at the bottom and out at the top)

Pay attention to the doors at the at the stairwells. Puff them. If lots of air is traveling up, that’s all heat. Air comes in cold and leaves warm- you paid for that ride. 

The rule of Mother Nature is the colder it is the more the house will “stack” or act like a chimney. The basic definition of a chimney is “a vertical structure with colder temp outside and warmer temp inside—-presto you have a chimney. The taller the home the more we need to concern ourselves with stratification 

I bet the rad in the entryway is pulling some good BTU. But if the stat is in an interior area. It’s probably a smaller piece of the pie.

if you can get a blower door test and or an IR camera you can put away your pack of Marlboros. 

Also- if the upstairs tenant is keeping their heat set low- presto—-you’re likely paying to heat their place too. Assuming there’s no insulation between the units. 

Here’s on of my tenants apartment- this is the range hood. They are complaining about their high gas heat bill for their 650 Sq ft apartment. The fan is running extremely often. I wish I left one probe out in the breeze, I could make a general guess at how many dollars this fan is blowing. (Cfm x deltaT x 1.08 = BTU)

Ironman

You you really need to heed the multiple comments about a heat loss calc or an energy audit. You're blaming everything on the boiler (a common assumption) when the majority of the issue is the load imposed upon it: ie, the heat loss.

Example: I have a Ram dually with a 6.7 liter Cummins diesel. It gets about 17-18 mpg on the highway with no load on it. If I pull a 17k lb. trailer, it will use twice as much fuel. There’s nothing wrong with the engine, it’s just simple physics that it’s gonna take a lot more fuel to create enough energy to pull a much heavier load.

Even a properly sized single stage boiler is over-sized 97% of the time. If it takes 100k btus to heat a house when it’s zero outside to get  it to 70* inside, then it would only take 50k btus when it’s 35* outside. The boiler is 50% over-sized at this temperature, but it has to be sized for the coldest night of the year (0* in this example).

As stated, the reason your not getting enough heat out of your BBS with 180* Supply WaterTemp is because they’re either in need of maintenance or they’re under-sized. Turning up the SWT encreases their heat output. Again, that has nothing to do with the boiler, assuming it’s large enough.

Will an over-sized boiler use more fuel? Yes, to some degree, but not that much.

What we’re trying to get you to see is that the boiler is the lesser part of the equation.

It’s also possible that you have a gas leak or faulty meter (unlikely, but possible). Or as suggested, a lot of the heat that you’re producing is going upstairs.

HomerJSmith

It appears to me that you are pumping into the expansion tank. It's that big round gray thing sitting on the floor. It also appears that the pump is a Taco 0010?

I would move the connection of the expansion tank to the input of the pump. Funny thing happen in the circuits when one pumps into an expansion tank. I would set the air charge on the bladder side of the expansion tank to 15 psi and set the pressure reducing valve (cold water boiler feed) to 15 psi, too.

I see this so often, usually on older sys, but I have seen this on newer installed sys, too. It's usually plumbers rather than hydronic specialists that were the installers.

JUGHNE

Does anyone think that there is a piping bottleneck on the return to the boiler?
Two 3/4" returns thru 3/4" pump flanges and then into 1 1/4".

Are there 2 lines coming off the supply? can see one but maybe the 2nd is hiding behind the flue.

GW

Fixing the piping and all of its non perfections would not change the high fuel bill much, will it? 

Tuto0174_

Thanks to everyone for the feedback. It makes sense to start with a heat loss evaluation. I will work on that before considering purchasing a new boiler!  The feedback regarding the boiler and piping is very much appreciated. I want to get this right for next winter. I am very new when it comes to basics of boilers and maintenance. See more pictures on piping.

JUGHNE

GW, now we see, it looks like only one 3/4" supply going up thru the ceiling, two 3/4" returns thru ZVs to pump.
The word of "constipated" has been applied to steam main vents that were too small.
Perhaps applies to water flow reduced and not picking up the BTUs.
Hotter boiler, higher flue temps and longer run time? IDK

Tuto0174_

It sounds like you noticed something. Honestly, I didn't understand anything you said lols. I am not an expert, I'm a newbie at this.

EBEBRATT-Ed

@JUGHNE

I agree. Piping looks too small for the size of that boiler. Boiler limits out stack temp high constant short cycling. Like parking your car against a tree and pushing on the gas pedal. You burn a lot of fuel and don't go anywhere.

Seems like someone missed it on the heat loss, baseboard and piping

GW

well- does one dump some dough and try to clean up the piping/system, or, cut the bait and do it all at once (new boiler as well)? I'm glad we (still, at the moment) live in a free economy and we all get to choose where to spend out money with with whom to spend it.

GW

@EBEBRATT-Ed it was prolly heating the whole building at one point. Them there pex lines sure aren't original. Someone made a less than ideal system 'less ideal' when the place flipped to a 2-family.

Lots of issues-
too bigga boiler
water temps are excessive to heat the place
Excessive heat loss or lack of heat emitter (or, the existing emitter is all jammed up)
Unsure where the 2nd fl occupant had their stat set to.

I suspect the zones aren't that big/long, so fixing the piping may not do much at all.

JUGHNE

But in any event, the ceiling would have to be opened to see where the zones are teed together.
It would be a start. Perhaps increasing pipe sizes would improve things a lot.

Relocating the pumps, air tank connection and air scoop would be done if boiler was sized down.

Ironman

I maybe seeing it wrong, but are both water heaters coming off of the same gas line?

@Tuto0174_
Are you sure that the heat for upstairs is coming from a separate gas furnace and not from a hydro air unit that's connected to one of the zones on your boiler?

Tuto0174_

@Ironman both water heaters and boiler are sharing the same gas line, each has independent shutoff gas valves. The second floor has its own furnace, it's in the attic, it's a small modern unit. It seems like at one point this boiler heated the whole house as we have baseboards on second floor but those are not being used as we now have forced air up there.  I appreciate everyones input!

JUGHNE

So then there are 2 gas meters on the building?

It is possible that some or all of the 2nd floor BB heaters are still connected to this boiler??

If so this would amplify the issues you are having, considered you are trying to push all the heated water thru one small 3/4" pipe.

Tuto0174_

@JUGHNE Baseboards in 2nd floor are not operating at all. Yes, we have 2 gas meters.

EdTheHeaterMan

JUGHNE said:

Does anyone think that there is a piping bottleneck on the return to the boiler?
Two 3/4" returns thru 3/4" pump flanges and then into 1 1/4".

Are there 2 lines coming off the supply? can see one but maybe the 2nd is hiding behind the flue.

My first thought when I saw this picture.

looks like someone did not do their homework when it comes to boiler installation. The pipe that is going into the circulator and the pipe coming out of the circulator can only handle 4 GPM which is about 40,000 of the 124,000 BTUs the boiler is able to put into the house. So that boiler is going to make the water very hot very fast but the pipes can't get the heat into the house. This is like buying an Indy race car to drive on a gocart track. Lots of overkill and wrong race track. You need a new boiler and a person that knows how to pipe them in.

My father used to say "If you want to lower your heating bill, look at the heater first to see if it is inefficient. Get that right the then can go to the windows, doors, caulking, insulation,

But he sold heaters... not windows or insulation.

Here is a chart on pipe sizes and the amount of heat that are able to carry.


Respectfully submitted,
Mr.Ed

Tuto0174_

@EdTheHeaterMan I can clearly see your point and it makes sense.. Many contractors will tell you/do what is easier for them, not what is best for the customer. I am sure that's what they did in this case.

What would be a better piping size to improve circulation? Any other suggestions to improve circulation/piping?

I appreciate your illustration and expertise.

Ironman

If both water heaters are on the same gas line, then you're paying to heat the domestic water for upstairs. Domestic usage is typically 30% of the gas bill. 30% x 2 = 60% of your bill is domestic.

No doubt there are issues with the boiler, but there's a huge part of your bill.

EdTheHeaterMan

You need a new boiler to save the most but you need to upsize the near boiler piping in order to get more heat from the boiler to the space you want to heat. Assuming you have near the correct amount of emitter capacity and that each zone is requiring at least 3 GPM but no more than 4GPM (the maximum of 3/4" pipe), then the common pipe from the pair of 3/4" loops should meet at a 1" minimum diameter pipe as illustrated. The pump outlet should also be a minimum of 1" to the return of the boiler. This will allow more of the boiler's capacity to reach your heat emitters. The restriction is less now.

Since 3/4' pipe can provide no mere than 4 GPM the both of them operating at the same time will only have a total of 8 GPM. Since 1" can handle 8 GPM under normal conditions, then there is no reason to go any larger. 80,000 BTU is still much smaller than the 124,000 capacity the boiler can provide, but that is all the capacity the existing pipes can handle.



This will get you a little relief but if you are going to drain the boiler to make those repairs, and that is all you have in the budget, then a little is better than nothing.

BUT... Your heat loss calculation is an important first step. I am only guessing about your emitter capacity. You may only have 30 feet of working emitters on each loop, and that means your pipes are just fine. That 3/4" pipe can handle between 65 to 70 feet of total lineal feet of baseboard emitters. My assumption is that you have over 100 feet of baseboard emitters. that common 3/4" pipe won't do 100 feet of baseboard radiators.

Here is another chart showing the number of lineal feet of baseboard each pipe size can handle

The top section shows that 3/4" pipe can provide enough heat to supply 67 Feet of Baseboard while 1" can provide enough heat for twice as much radiation.

HomerJSmith

I think I would measure the baseboard temp on each circuit. I would take the temperature of the output of the boiler, the input to the first baseboard and the output and go around the whole circuit (measuring) back to the boiler return. I wouldn't rely on the gauge for the supply temp as it may be inaccurate because of the age.

You can get a laser thermometer at Harbor Freight, Home Depot, or Lowe's for cheap.

If you use it put a piece of black electrical tape on the pipe where you shoot it. That would be more accurate than a shinny copper pipe. Report back on your findings. I just want to know if you are getting enough btu's in the building. I would think that a 165K boiler is adequate for 1700 sq' at up to 2500' altitude above sea level.

My 3200 sq' house is a little less than 7000' above sea level and I have a 140K boiler derated 12-14% for altitude with an occasional -10 deg week. I never run out of heat in the house and the boiler also provides heat energy for a 45 gal indirect water storage tank. I never run out of hot water.

It is well insulated and when I built it I put in a lot of baseboard which allowed me to put out the btu's necessary at a lower water temperature.

If you can't meet the thermostat setpoint except with 200+ supply water, you either don't have the baseboard or you don't have the flow. I'm assuming acceptable insulation.

So, the questions are: Why do you think you're using too much gas? and Why do you think it is the boiler that is the culprit?

If I missed the answers somewhere in this post, forgive me.

EdTheHeaterMan

After our PM I feel it is a good idea to let everyone who is interested in helping you understand your situation. There are only 2 loops on the boiler, one has 24 feet of element and the other has about 40 feet of element. The rooms are comfortable at low outdoor temperatures so the amount of heat emitters are adequate for the space being heated. All rooms are comfortable.

The total BTU of the existing heat emitters are less than 40,000 BTU total for both zones, so the 3/4" pipe is large enough for the entire system.

The boiler was re-commissioned many years ago from serving the entire home to only the two zones, basement, and first floor.

This leads me to recommend a new boiler that has about 50,000 BTU input @ 80% AFUE to provide all the heat the pumping can handle. I also recommended a load calculation just to be sure that there is no room for improvement by adding more baseboard emitters to some of the living space. If the total emitters stay at 64 feet then he is good to go. If the contractor recommends more lineal feet of baseboard element, then the piping may need to be larger where the common piping connects to the boiler. but for now, it does not appear that is the case.

Since most of the ultra-high efficiency boilers are all going to be way oversized, I believe that the economical 80% boiler will be just fine and also keep the water heaters from becoming Orfined Appliances in that existing chimney. A liner may still be required with the reduction of the total BTU capacity of the chimney

Respectfully Submitted.
Mr.Ed

PS With this information @Tuto0174_ can make a well-informed decision with the new boiler. And you should look into the water heater gas supply situation at the time. You might be paying for the other tenant's hot water. Close the gas valve to each water heater for a day or so and see if the other tenant complains about no hot water. If they do then tell them your gas is being serviced and maybe they should get their water heater on their own gas meter.

Tuto0174_

I am very much thankful for everyone's feedback. I have learned sooo much and I am confident of my next steps. I will plan accordingly before next winter hits.  Great forum 👍!  Special thanks to @EdTheHeaterMan.

EBEBRATT-Ed

@Ironman & @Tuto0174_

I asked about the gas meters and what is connected to them sever posts back.

Still not clear on that.

The op said the water temp used to be set at 200 and has been lowered to 180 and the house heats worse since that has been changed.

If that is the case then the piping/baseboard is likely too small.

First thing is a heat loss. Then take it from there

HomerJSmith

I'm not so sure what the boiler or heat emitters sizing should be. A whole house heat calc on the coldest day of winter would tell me how much + 10% based upon flo and SWT.

At 200-210 deg that meets setpoint tells me he need more heat emitters that could run at lower temps. Running a boiler so high is inefficient and costly. The thermostat that's never satisfied is telling the boiler to over produce.

Of course, I wonder about those two, what appears to be 60 gal, water heaters.

bio_guy

I wonder if there were ever indirect water heater(s) installed. That would tend to make the boiler closer to the right size.

Tuto0174_

Based on feedback obtained here and the contractor I hired, this is the progress we made! Things are looking much better now.