Oil Fired combi boiler?

Actually what you have is pretty good — a quality modern oil boiler firing a hydronic system. The downside is keeping the boiler warm for the domestic hot water. You might gain some efficiency by using an indirect hot water heater, such as a SuperStor, heated by the boiler but storing a good deal of hot water, like a regular hot water heater. It works like a separate zone off the existing hot water heat.

What you will NOT find is an oil fired "combi" in the modern usage of the word — which also implies "mod/con" — that is modulating. Those do have slightly higher rated efficiencies, true — but they are only for LP or natural gas, as modulating an oil burner is really remarkably hard and there isn't that much to be gained anyway (oil is naturally more efficient that either LP or gas under otherwise identical conditions).

@TdiGuy

Yes EK is the way to go, or you’re going to have to go to Europe or Asia for one.

I have a Bock tank which I use for hot water and hydro-air. I think that a switch will not save you any significant amount of oil. Perhaps changing equipment is not the best cost saving approach. Are you using a "full service" oil dealer? You could be paying for high cost services you are not using. I use a pay as you go dealer and rely on my plumber for service. There are also independent heating service companies. Pay as you go dealers are usually have a much better oil price. Also, consider if you need annual service calls. I only have my equipment serviced every other year because of low operating hours. I heat with wood

Hay @TdiGuy, An oil-fired boiler with a tankless coil is about as close as you are going to get to a combi system with oil heat. However, I would not recommend that approach.

Where are you located? What is the price of Fuel Oil v. Electric in your area? And finally: Do you use wood heat to reduce your fuel oil usage? Answering those three questions will send you to or away from some suggestions above.

Gas-fired mod-con combi boilers are a step above that because they do not maintain a minimum water temperature the way an oil-fired boiler with a tankless coil does. That is why I say they are a step above. Even so, I still would not recommend a combi system, for at least two reasons.

The expected life of a tankless water heater is generally less than 17 years, even if all the required maintenance is completed properly during that time. With a combi system, both the heat and the domestic hot water come from the same device, even though those two functions have different demands and different potential problems.

Either the heating side or the domestic hot water side could become the determining factor in replacing the entire heat and hot water system. An expensive failure any time after the fifth year could mean buying a complete new system. That could happen because of a failed control board related to the heating system, a domestic hot water problem caused by improper heat exchanger maintenance, or any number of other issues that can occur.

That said, an oil-fired boiler that maintains a minimum temperature for domestic hot water all summer long is, in my opinion, a waste of energy. In most cases, that boiler is connected to a chimney. The chimney continues to draft, pulling heat out of the boiler’s heat exchanger while cooler basement air is drawn in to replace the warmer air going up the chimney. That standby loss can cause the burner to operate every four to six hours just to recover the heat lost up the chimney, even if you dont open a hit water tap during that time.

If you were going to install a gas-fired mod-con boiler, I would choose a heat-only model and connect it to an indirect water heater. That would give you the energy-saving benefits of outdoor reset control and the small water content associated with mod-con boilers.

Since you are suggesting that you want to stay with oil heat, I would choose the most efficient cold-start, heat-only oil boiler available in your area and connect it to an indirect tank for domestic hot water. That will get you as close as possible to the most energy-efficient oil-fired system you can have.

The burner is large enough to heat your home, so it has more recovery capacity than an oil-fired stand-alone water heater. The indirect tank is not connected to a chimney or any other vent system, so the standby loss is measured over a much longer period, often 12 hours or more, and as much as 20 hours on some well-insulated models.

That means if you go away for the weekend and forget to set the water heater to a lower temperature or vacation mode, the burner may only operate once for less than ten minutes every 12 to 20 hours to make hot water. That is very different from a tank of hot water connected to a vent system that can constantly pull heat up the chimney.

The main heating boiler can operate as a cold-start boiler, and the boiler temperature can drop as low as the basement temperature during that standby period. That will vent far less energy up the chimney than keeping a boiler hot all summer just to maintain a tankless coil.

Indirect water heaters also tend to last longer than tanks that have flames directly under them. Some even have lifetime warranties. It might be the last water heater you ever purchase.

Energy Kinetics has one of the best offerings, as you may have seen in a previous post. I would look closely at that one. Your fuel dealer may wonder if you started buying fuel from someone else!

In eastern Massachusetts and in the area right around the Connecticut River you could probably get off oil with a cold climate heat pump or heat pumps and a heat pump water heater. You would NOT be getting off oil (or gas), as that is what much of the grid electricity you might use comes from. But it wouldn't be that much more oil or gas (power plant efficiency vs. heat pump efficiency is close to a wash in cold weather!). Now if you had enough solar PV and enough battery storage you could go off grid, but the capital investment to do that is very high.

Elsewhere in the State you are going to need a backup/cold weather heat source — so keep the oil for that. Mini-splits or more complete heat pump coverage can keep you somewhat warm even in pretty chilly weather — that's a matter of setting thermostats and warm sweaters and the like.

The EK boiler would be a good match but how can you justify the expense for DHW? An oil fired HWH would solve the HW issue but not give you BU heat.

You could keep the boiler for BU heat, disable the tankless heater and put in a Heat Pump water heater. The cost of operating the HP water heater operation will be offset by your solar if the HPwh can't keep up.

https://hpwhcalculator.ri-app.com

How is the solar PV penciling out? How long hasn’t been online?
if you have excess generation, and the feedback deal is not great, even a resistance water heater might be worth considering.

Your inverter software or utility bill should show consumption and feed in.

We have a summer and winter power rate .13 or .15. But feedback is.05!

They make an assortment of HPWH in regards to power required.

They have models that run on a 15A 120V all the way to a 240V 20A circuit, some are classified dedicated circuit models.

Obviously the low power draw would be slow to recover if it depended on the resistance element back up.

In areas where off peak rates apply, HPWH owners allow the tank to run to 140- 150 on off peak. Then add a 3 way mix valve at 115- 120F to extend the tank drawdown.

Where the tank is located has a lot to do with a successful installation. it has to pull heat energy from SOMEWHERE.

Also if you are used to large dump batches of DHW, like filling a large tub, the tanks are slow to recover.

I had a sample low current model.Filled it with 55° water, it took over 8 hours to get to 120°! This was in HP mode only. Some tanks kick in a backup element to speed recovers. But efficiency drops, you don't want that with your power rates.

Your average incoming water temperature has a bit to do with recovery.

So do some homework before buying a HPWH:

The amount of water you are used too.

Where the tank will be located.

Power available to supply it.

If you have a 150 amp panel you should have plenty of power. You may be able to get creative and use some tandem breakers or add a sub panel off the 150.

Changing the entire panel may open up a can of worms like an outdoor disconnect and other thing that are ridiculous and cost $$$

Unless you define your DHW load, we are just guesstimating.

The common aoppoch, if you have the room is a large tank, 80 gallon at elevated temperature. This give you some dump load for a tub fill and leaves some additional water.

My 50 years experience tells me people get accostomened to the amount of water you provide them.

Give them a 40 gallon tank, they use all the water.

Give them 150 gallons and they use all the water.

It may be a learning curve with a HPWH if you are used to endless dhw.

The online free Lochinvar calc (lochinvar toolkit) shows the effect of elevated tank operation.

So the 80 becomes a 99 gallon tank when mixed down rom 140- 120.

Keeping in mind the 80 will take longer to recover thn a 50, like through the night hours or more!

OMG. I was unable to post on this thread and all of a sudden my post that would not show just showed up. That was weird.

If you are going to tow a trailer with fuel on it, check your local and State laws VERY carefully. There may be an upper gallon limit (typically 100 gallons) that you are permitted to have without a CDL and certification for handling fuels.

Also check your truck's insurance. If you are not specifically covered for auxiliary fuel tanks or transfer tanks, you aren't covered at all, and your liability exposure is going to be huge.

And once you have all that nicely lined up, please do the rest of us a favour and go and take a few lessons on handling a trailer with a significant volume of liquid on it. They don't trail the way an ordinary load trails, and not to put to fine a point on it i don't want to be behind you when it starts to sway and you jackknife it.

@Jamie Hall said: "@EdTheHeaterMan 's picture of 4 55 gallon drums on a utility trailer terrifies me."

That s the point.

Now lets see how the numbers work out.

Retail oil price delivered in your area. You recently paid about $900.00 for 200 gallons that is roughly $4.50 per gallon.

You mentioned that you could get diesel including the road tax for less. According to the information available Diesel at the pump is approximately $5.50 per gallon in your area, but a month ago it may have been less. So lets say it is actually $4.28 per gallon.

An you burn maybe 600 gallons per year.

That is $4.50 less $4.28 or a difference of 22 cents per gallon.

a 100 gallon tank will hold about 95 gallons. (you need some air space for expansion) so that is about a savings of $20.90 per load of fuel. That is a savings of $125.00 to $130.00 per year.

Now lets look at the cost of that trailer you want to get. eBay has several used utility trailers for around $1200.00

There is a used 135 gallon aluminum diesel truck tank for about $395.00

then a diesel hose to connect to the bottom of the tank at about $45.00

Perhaps some lumber and hardware to make the tank permanent for $150.00

That comes to about $1,800.00.

At a savings of $125.00 per year, you will save enough on fuel in about 15 years to pay for that investment. Then you can start saving big time.

Maybe if you were to let your friends use the trailer for a fee, you can recoup a few years sooner.

Of course, you might need to repack the trailer wheel bearings, fix a busted tail light or even change a flat tire over the 15 years. But still…. You are saving big time on that fuel.

In my experience just sign up with a decent company for automatic fill and then you don't have to deal with these issues.

You're not saving $$$ going with a cheaper company that doesn't have any service. If you are an established customer, they will not want you to run out of fuel.

The oil meters on the trucks are sealed and checked yearly so the oil company is not robbing you.

If you are not a regular customer, why should they rush when you call?

@TdiGuy said: "There is one really big factor thats not being accounted for here also. Not having to rely on someone else and their annoying habbit of having next to no communication. It might as well be a 1 way street when it comes to talking to fuel oil delivery companies. I call request a fill then hope to hell they respond within a day or 3 never knowing when they will show up. "

Then you are purchasing fuel from the wrong oil company.

When I was driving a fuel oil delivery truck, we scheduled deliveries to the exact minute. None of this “sometime Tuesday” nonsense. If your appointment was for 2:15 PM on Tuesday, we were there at 2:15 PM on Tuesday. Not 2:14. Not 2:16. At 2:15 you could practically set your watch by the sound of the truck backing into the driveway.

It was a difficult company to work for because the boss would hand you the schedule and apparently expected you to obey the laws of both transportation and physics.

I remember talking to drivers from other companies at the loading rack, and they thought we were completely insane.

“You mean the customer knows when you’re coming?”

“Yes.”

“And then you actually show up then?”

“Yes.”

“What kind of communist operation are you running over there?”

But my boss took the customer’s concerns seriously. He used to say, “Our customers have lives too. We can’t expect them to sit in the front window all day staring down the street waiting for an oil truck like a Labrador waiting for its owner to come home.”

We charged a premium for our fuel because we provided premium service. You made an appointment, we delivered the oil, and then you were free to continue with the rest of your life.

No fasting. No prayer vigil. No burning a candle in the window hoping the fuel truck might appear before Thursday.

If you had a 2:15 delivery, you could schedule a dentist appointment for 3:00, dinner for 5:30, and your second marriage for 7:00 with complete confidence.

Apparently somewhere along the way the fuel oil industry replaced “appointment” with “we’ll get there when we get there.”

So yes, if ordering heating oil currently involves calling the company, leaving a message, checking your tank gauge every 20 minutes, staring out the window for three days, and eventually seeing a truck pull into the driveway like the second coming of Christ...

You need a better oil company.