2500 gallons 3500 sq ft

Oilhog

Hi all,
I bought my house in Dec 2019, and each heating season I consume about ten tanks of oil. The house is a split level, 3500 square feet (plus a 1600 square foot garage). The system is hydronic, the boiler is a 2007 Vitorond 100 with a Riello burner, there are three air handlers, 4 circulators (plus 1 for indirect water heater) and 7 thermostats (plus 1 in the garage for the unit heater).

I have had the oil company here, HVAC people, energy auditors, and the best so far, "Dr. Energy Saver" (DES). DES blamed the insulation so I paid $18,000 for attic insulation. They did very high quality work which was completed last February. I noticed a big difference in the house so I don't regret doing the work, but I have still consumed a surprising amount of oil since.

From May through September I used a quarter tank for the water. In the past 4 weeks I have used 1/4 tank and the heat has only run at night. It seems like the unit consumes a lot even when demand is very low. It makes me think the thing has a massive nozzle or something but I would expect to see that in the combustion tests.

Speaking of combustion tests, everyone that has performed one (at least three people) have said that they "...don't recommend upgrading to a new boiler..." and that "... you're not going to get any better efficiency on oil." One mentioned that the nozzle size was small but that the pressure was turned up so "it's the same thing."

My question is, is this level of consumption normal? I don't know anyone else that uses anywhere near what I use. I am not looking to save a tank or two per year or something, I just want to know if something is really wrong. I can't think of anyone that uses even half of what I use.

Thanks in advance.

bburd

When was the house built? Where are you located?

Hot_water_fan

That’s very bad usage. Do you heat the garage? Have you performed a blower door test? What was the result? 

Jamie Hall

That is very high usage -- but don't blame the boiler. It's trying to keep you warm, but you are losing heat in large quantities somewhere, and that's not its fault.

you don't mention what efficiency you are getting -- the apparent efficiency should be on the combustion test printout (if you didn't get one -- or worse, didn't get a combustion test with the proper instruments, you need one).

The gallons per hour which a nozzle will provide is based on both the nozzle size and the pressure it is run at. Nozzle size is usually shown as so and so many gallons per hour -- but that is measured at 100 psi, and will be more if the pressure is higher, which it usually is, to get better atomization and combustion.

Oilhog

The house was built in '76, but it was a small house which has had significant add-ons. One in '94 and the other in '08. I'm in CT.

The first winter I did not heat the garage, but the heat was unable to keep up in the west wing which has the garage under it so I turned the garage heat up to 55-60 degrees to help. The energy people performed the test, I asked how it did and they said there was no significant indication of a problem. I don't recall the numbers but may be able to look them up if you think it's important. The energy auditors also sold me on sealing the lower level air handler, so that was done.

bburd

Is the system losing water? In hydronic systems with buried pipes, a water leak may go unnoticed and be made up by the automatic fill valve. This can lead to enormous fuel bills if there is a significant water leak. You may want to check your water meter when all taps are turned off.

Oilhog

I have a well, no meter, but I do have a radon remediation system for my water which is quite loud. So if water runs anywhere I hear it. For example my wife has left the garden hose on and we quickly realize it when that system fires up. Because of that, I don't believe that could be it, at least not to a significant degree.

Jamie Hall

You are in Connecticut? Then that oil usage isn't just very high -- it's nuts. To give you perspective, that's what is used to heat the main place I care for. Which is 7,000 square feet, not 2,500, and was also built in '76 -- 1776, that is, with additions in 1875 and 1893, And is NOT insulated.

Oilhog

Holy cow, Jamie. I bet that house is beautiful. Yes, I suspected that it was absurdly high which is why I mentioned that I'm not looking to tinker with the house to save a little bit here and there, I am looking for the main cause of such high usage.

Hot_water_fan

My suspicion is the garage heating portion - if the door is leaky, you’re basically heating Connecticut. Is the garage ceiling insulated? It’s very possible the blower door test was on the house and the people door is tight enough but the car door isn’t. 

Oilhog

The garage is insulated, sheet rocked and has a tile floor with a radiant heating system installed but not hooked up (along with the functioning unit heater). The previous owner intended to keep the garage completely climate controlled.

DJD775

I'm in RI and have lived in 2 houses and oil consumption has ranged from ~38%-45% of my square footage. Both houses had oversized conventional oil boilers. The boiler you have is a modern 3 pass boiler so there is no reason to change that. Even if the boiler is oversized, which they most often are, that would not explain the excessive oil use.

WMno57

Do you have a water softener? Is the boiler on softened water? Softened water corrodes boilers.

Oilhog

I do have a softener, yes, I am not sure if it goes to the boiler but I can certainly check. How would I diagnose or find the corrosion?

Oilhog

Regarding the combustion tests, I did not get a print out, but every person that conducted the test concluded that the efficiency was as good as it gets, and each person was notably surprised by the result. One person was my neighbor who is a commercial plumber. I could ask him if he recalls the result.

bburd

If the system is partly hydro-air, is the ductwork sealed and insulated? Does it run through unconditioned space?

ScottSecor

Is your only source of heat the three air handlers and the unit heater in the garage? I ask, because this is a bit unusual for a house in the northeast. I also ask, because you may have built in fresh air that is mixed into the ductwork? Most large homes we worked at with hot water coils and ductwork also have radiators, or baseboard, or flat panel radiators or radiant heat.

Is there any chance that you are running the boiler through out the entire heating season at say 180 degrees and 'blending' in cold air from outside to the ductwork. In much older homes and some very high end homes this was done to prevent the spread of disease/mold, etc. I doubt this is the case, especially with a house that is less than fifty years old.

Hot_water_fan

The unit heater is part of the boiler system? Or separately fueled? 

Oilhog

The first three winters the duct work may not have been sealed and two of the three air handlers' ducts were entirely exposed in the attic (unconditioned space). After the DES work, the ducts are all buried in 16" of cellulose insulation, and the lower level air handler was sealed at around the same time, so this is the beginning of the first heating season after all the work.

Oilhog

There is one room which has radiant heat. It is a Brady Built sunroom. Other than that only the three handlers and unit heater. The unit heater is part of the boiler system.

Oilhog

Worthy of note: The boiler is all the way in the lowest level of the house and all the way to the East. The West side of the house has the air handler in the West side attic... it's a bit of a distance, yet all the circulators are the same. Odd?

Oilhog

Unit heater is also on the West side, and must be on for the West to maintain temperature.

Hot_water_fan

Worthy of note: The boiler is all the way in the lowest level of the house and all the way to the East. The West side of the house has the air handler in the West side attic... it's a bit of a distance, yet all the circulators are the same. Odd?

Longer distance -> more friction -> lower flow rates for equivalent circulators -> lower average water temperature -> lower btu output. But it’s usually marginal. 

Robert_25

No, that level of oil consumption is not even close to normal. Assuming the boiler is running well and the wind is not blowing through your house, to burn that much oil your heating system is somehow putting a BUNCH of energy outside the insulated envelope of the house.

Uninsulated ductwork in the attic is bad, but the air handler sucking cold air from the attic is worse. It is critical that the ductwork is sealed.

You mentioned a radiant slab...if there is no insulation under the slab that could be sucking a large amount of energy as well.

ScottSecor

Are the pipes that feed the air handlers in conditioned space or the attic?

Are they well insulated or are they losing tons of BTU's before they reach their destination?

Is the house comfortable throughout the heating season?

Can you easily satisfy every heated area regardless of outdoor temperature?

I just spent thirty seconds looking at the Brady-Built website for clarification. I'm guessing that this room alone may cost you a few tanks of oil per winter to heat. Perhaps I'm mistaken and the windows are much better than the ones I've been in locally.

I also have concerns with your garage heat. How often do you open one or both garage doors? As you can imagine, every time you open that door a lot of heat escapes. Most older garage doors are not well sealed and certainly not insulated.

WMno57

Oilhog said:

I do have a softener, yes, I am not sure if it goes to the boiler but I can certainly check. How would I diagnose or find the corrosion?

If the boiler has had softened water for the last 15 years, then it may start leaking soon if it isn't already.
To find if there is a leak, the procedure is to shut off the water feed to the boiler and see if there is a pressure drop on the boiler gauge. If it holds pressure for a day of two, then probably no leak.
Keep an eye on it, don't let it dry fire. Your boiler should have a Low Water Cut Off (LWCO) but lets not assume it works. Your boiler professional who is maintaining this money eating beast can help you with this test.
I'm thrifty and try to avoid spending money just to raise efficiency, but given the amount you spend on oil, two new systems should be considered:

• Heat Pump Water Heater for domestic water.
  
• Heat pump for space heating Spring and Fall.
  

First, let's identify whats wrong with the current system.

Oilhog

The radiant floor in the sun room does not have a foundation under it. I believe the sun room is a contributing factor, however the room only runs the heat at night. The room is on the South side of the house and actually makes a ton of heat on sunny days. Even on cloudy days the heat does not run in there.

The attic air handlers may suck up some attic air, but not a significant amount. There are returns only in conditioned space, so the only attic air would have to enter through a leak in the ducts. People have visually inspected and reported that there are no significant leaks.

More than half (at least half) of the pipes are in conditioned space before entering the attic. This winter the pipes will be buried in insulation, but they haven't been in the past.The only areas in which the pipes are exposed is within the envelope of conditioned space now.

The house is much more comfortable since the work was done. No more drafts, no more ice dams on the roof (so far). As mentioned, I cannot satisfy the west wing of the house unless the garage is heated, however this year may be different since all the work was done.

The heat is turned off over the past 4 weeks in the sun room (no need for it anyway), yet I have used a quarter tank just for a few night time cycles over that time period.

Garage doors don't open frequently. The heat runs at night mostly. Might cycle a couple of times throughout the daytime. The temp is set for around 60.

Oilhog

Also note that the first winter I lived here the garage heat was inop. and the oil truck was here every two weeks anyways! (It was that same winter I learned that the heat couldn't keep up).

ScottSecor

@Oilhog the reason I asked if you could easily heat the house is twofold. If the flow in the piping to the air handlers (that go to the west side) is inadequate, the thermostat for the living space in this zone may never get satisfied on a cold winter day. If this is the case and the air handler, ductwork, etc are sized correctly you may need better water flow. In simple terms, if the boiler is producing 180 degree water and the water is only 150 degrees by the time it enters this heat exchanger, there may not be enough energy to heat the space. On the other hand, if the water entering the hx only drops to say 178, the water temperature (flow) in likely not an issue.

Oilhog

I suspect that the flow is insufficient. I also believe that the unit is small for the space. Assuming the worst, could this result in such a ridiculous level of fuel consumption?

Hot_water_fan

I suspect that the flow is insufficient. I also believe that the unit is small for the space. Assuming the worst, could this result in such a ridiculous level of fuel consumption?

Nope, would actually lower consumption if the output was below the demand. 

ScottSecor

IF the thermostat is rarely satisfied, the circulator would run non stop, and the boiler would run often trying to satisfy the load.

Imagine your driving up a steep long hill towing a heavy trailer. If you don't have enough power to overcome the load and incline, you will never make it to the top of the hill. In 'normal' heating systems, the thermostat (top of the hill) is eventually satisfied and you stop using oil and electricity for a little while until the next cycle (as you coast down the hill). In your case that next cycle may never come on colder days (thermostat calls non stop).

I suggest you reach out to a contractor on this site and get a consultation. Ideally they would do a site visit on a cold winter day. I think a professional that specializes in hydronic heat will be able to determine the root cause of your excessive oil consumption.

Oilhog

Thanks Scott. I have tried several people. I have come here after tens of thousands of dollars and professional after professional. It all goes the same way:

Professional shows up, I say how much oil I use, eyes bug out of head, I walk through, they poke and prod and test this and that, and when they are ready to give up they tell me that they now realize that ten tanks must just be normal for my tall ceilings.

One of my neighbors is a professional plumber for a major company and a friend, I have a good friend that manages the oil company I use, my other neighbor owns an oil company, I have a customer that is a heating and A/C specialist, I have had their friends which are professionals come... all the same stuff. over and over again. Insane.

ScottSecor

One more thing to consider. While many high end homes utilize ductwork for heating (and cooling) it may not always be the most efficient method to heat a home. I do not have data at my fingertips right now, but I suspect your air handlers require a minimum of 140 degree water to provide adequate air temperature. Most of the older systems I have worked on (mostly commercial or enormous homes) with this type of heat emitters require a minimum of 180 degree water on design days. With a well designed radiant system you can sometimes get away with 100 degrees. With radiators, you might get away with 140 degrees.

What I'm getting at is your system likely requires the hottest water temperature (uses the most energy) to make the house comfortable. Maybe connecting that garage radiant heat or a few well placed heat emitters could pay for themselves.

Oilhog

There is a sticker on the air handler that reads "180 degrees maximum"

WMno57

How tall are your ceilings? How many cubic feet are you heating? Has anyone done a heat loss calculation on your home? Heat Loss is the number of BTUs required to maintain room temp on the year's coldest day. There are programs to estimate this. They consider insulation, windows, sq feet, cubic feet, and other construction details.
2500 gallons of B20 fuel times 127,250 BTUs per gallon is about 318 million BTUs per year. Some of that is domestic water, and some is going up the chimney. The rest is going into your house, or under it.

Oilhog

I have not had that done, however the addition done in '08 must have had it done to size the boiler and the West side air handler and the A/C unit. The build date on the boiler is '07 which lines up with that.

Hot_water_fan

I have not had that done, however the addition done in '08 must have had it done to size the boiler and the West side air handler and the A/C unit. The build date on the boiler is '07 which lines up with that.

Unfortunately, this step is often skipped or botched. However, that’s not causing you to burn 2500 gallons per year. How much of your house is glass? A split level should have some insulation in the walls, you have great insulation in the attic, but glass is not a good insulator. 

I’d consider ducted heat pumps in combination with figuring out where the btus are going. Oil is extremely uneconomic right now unless your electricity is sky high, like $.50+/kwh.

EBEBRATT-Ed

Do you have an underground oil tank that could be leaking?

The way to fix this is to start from scratch.

Do an accurate heat loss of the house
Determine if you have enough air handler & coil capacity to heat the house
determine if the pipe size to and from the ahus is adequate and insulated
determine if the boiler has enough capacity
determine how the boiler operates and is there some controlissue causing this
consider lowering the garage ceiling and adding more insulation. Any room over a garage can be tough to heat

Oilhog

I have approximately 870 square feet of glass, with 164 North facing, 475 South facing, 144 East facing, and 87 West facing.

No underground oil tank nor line, so no leak.

I suppose I could check the sizes of everything, but how far off would they need to be to result in such consumption? 1/3 of the system is under sized if anything and that seems to be something which results in less usage not more, right?

pedmec

This might sound like a stretch but i have found this to be an issue more times than i can remember. Have you confirmed that the air conditioning is not running at the same time as the heat. I have found this to be the problem with high fuel bills a lot, a real lot. And even professionals miss it because nobody is thinking of air conditioning in the heating season. everyone's gonna assume you can hear the condensers running but that not always true as I have found this issue multiple times