Helpful? 0

Looking to do away with my oil heat

Hello all, I was looking up information on Air Source Heat Pumps/Ductless minisplits, and stumbled upon this website, what a great find. Anyways, I’m hoping to get some information/advice as the best way to cut WAY down on my oil heat, so bear with me as this might get a little long.

First off, we live in Topsfield, MA (not Maine or Vermont cold, but this winter has been tough), there is no natural gas near us, kitchen stove is propane, and the house is a cape (built in 1962), with two large occupied bedrooms upstairs on the second floor, the main living area consists of a large living room, small kitchen/dining room, and two back rooms (office and guest bedroom), an unheated sunroom (with 3 huge old patio sliders off of the kitchen) and a partially finished (unheated) basement. The oil boiler (about 6 years old) is in good shape, runs at about 82% efficiency, and heats our really old Hot Water Baseboards decently, except for the upstairs units. The problem I am having is that there is only one thermostat (near the living room) and the upstairs rooms (our master bedroom and our daughter’s room) are always about 5-10 degrees colder than downstairs, I think because the thermostat is satisfied too soon. We just had a Mass Save energy audit and the house isn’t in that bad shape, insulation wise, we have to change out a few windows, do some air sealing and add little insulation in the roof/crawlspace.

So I have a couple issues I would like to solve….and am looking for some help from this site to steer me in the right direction.

1.First off we are going to do the insulation, weather stripping, and air sealing Mass Save suggested

2.I am thinking about buying a pellet stove insert (top of the line one, with thermostat control) for the living room which will heat most of the main floor

3.I am thinking of buying a (4) zone mini split system, with one condenser mounted in the back of the house, and with a head unit in each bedroom upstairs, one in the basement and one in the sunroom to provide heat to those areas, with maybe adding a solar array to help defray the electricity costs, bonus is we will have A/C during the summer

4.I would like opinions on what to use for hot water (efficient & sufficient amount) as right now our hot water comes right off of the boiler?
-On demand water heater?
-Indirect water heater off of the boiler, even though I’m hoping to cut the boiler usage WAY down
-propane or electric standalone water heater?

Looking forward to hearing your opinions, ideas on how to reduce, and maybe eliminate for the most part out oil usage. Thanks so much!!

Asked by Khouri Rice
Posted Mon, 03/24/2014 - 12:45


13 Answers

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Helpful? 0

Call me...

1 Change your heat to a two zone system. $1,000
2 Add ONE mini split for now downstairs and forget the pellet stove. $3,000


For bedroom air buy two small window units on sale in the Fall. $500

Khouri your list of do's would cost $25,000 and you would be feeding and not enjoying cleaning a pellet stove. No one likes a pellet stove long term.

Do my list not yours and you will be happy.. don't worry, be happy...

If my humor is misunderstood... listen folks... the is hanging on a wee bit too long. Gonna be close to 0 degrees tonight on March 24!!! Go away winter... see yaa next year buddy.

Answered by aj builder, Upstate NY Zone 6a
Posted Mon, 03/24/2014 - 13:13

Helpful? 0

Installing a single ductless minisplit unit in your living room would be a good place to start. If you do that, keep your oil-fired hydronic system -- just reduce the amount of finned-tube baseboard in the living room and move the thermostat upstairs.

For more information on water heaters, you might want to read All About Water Heaters.

Answered by Martin Holladay, GBA Advisor
Posted Mon, 03/24/2014 - 13:17
Edited Mon, 03/24/2014 - 13:19.

Helpful? 0

Thanks for the quick are my follow up questions to your responses...

Response #1 (AJ)
1. If I change my heat to a 2 zone system (which I looked into) that still means I'm using oil to heat my house, which I'm trying to reduce
2. Adding one minisplit to downstairs is an option but we did have a propane fireplace insert and we like the look of a fire, the pellet insert we looked at only has to be cleaned once a week, and is very efficient.

Aside from the water heater part, the cost (labor and materials) of the 4 zone minisplit and pellet stove after rebates, is $13,000, I calcualted that I would save about $1000-$1500 year over oil so a 9-13 year return on investment

Response #2
Single minisplit in the living room and then move the tstat upstairs? But then I would be still heating the upstairs by oil heat, any alternatives?

Thanks for the link, I will read the article

Answered by Khouri Rice
Posted Mon, 03/24/2014 - 14:04

Helpful? 0

The as-used efficiency of wood or pellet burning inserts can be well under the tested combustion efficiency, particularly when the chimney is on an exterior wall and uninsulated. The availability of pellets is often a problem too, especially at the end of a long and cooler-than-average winter. If you go that route be sure to stock up in the early or mid-season rather than counting on your supplier to have them in stock. In the past week there has been a serious run on wood pellets in MA, since the box-store outlets haven't replenished stock and are using the space for springtime product lines.

Pellet stoves also require electricity to operate, and one consideration for having multiple heat sources is to have something that could be a back-up when the grid goes down during a hurricane/blizzard/ice-storm. A wood-stove (or wood insert) would be a better option from that point of view. (Cord wood is also substantially cheaper than wood pellets on a per-BTU basis if you can find a reliable local cord wood supplier.)

The MassSave audits are only about grabbing the lowest-possible hanging fruit. If you're intending to heat with ductless you can probably dial it back to 1-2 heads from your intended four, spending some of the money that would have gone toward ductless heads (at $1.2-2K/per, installed price) on more serious load reductions in doored off spaces. Any room that does not have a design heat load of a LEAST 5000 BTU/hr @ +5F outdoor temps (approximately your 99% outside design temp in Topsfield) should not be a candidate for it's own ductless head, the smallest of which are ~7000BTU/hr. Oversizing a head for it's load cuts into efficiency AND comfort, and you may be better off installing radiant cove heaters correctly sized for the load, putting them under both occupancy-sensor and thermostat control.

AJ's recommendations are pretty good. A single mini-split sized for the average whole-house mid-winter load ( the load at about +25F, not +5F) would likely pay for itself in under 3 heating seasons in offset oil use, provided you have a sufficiently open floor plan that it wouldn't be grossly oversized for the space it can heat directly. A 4-head multi would take a longer (a LOT longer), but may still be worth it. But reducing the load and supplementing the doored off rooms with well-managed small-as-possible cove-heaters and pouring the real money into lowering the load further may be the better long term investment. It depends a lot on where the bedroom heat loads pencil out initially. If the first floor is fairly open and you can convection-heat the upstairs during the day by leaving the bedroom doors open you can probably cut your oil use by more than 3/4 with a single unit, but you'd probably still need something upstairs for cooling. Sensible cooling loads of houses with reasonable roof/attic insulation in MA are usually pretty small unless most of your windows face west, and AJ's cheap window-shaker solution might be the right thing to do there, or a 3/4ton-1 ton ductless head at the top of the stairs can probably cool the whole house, again, provided you're not looking at 300 square feet of "sunset view" glazing or something.

If those three sliders are single pane, (or clear-glass and facing west) it's probably worth biting the bullet on replacing them with low-E units rated no more than U0.32, adding some wall and installing swinging patio doors. A typical slider is about 50 square feet, and a clear glass double-pane would be about U0.5 ish, so with three of them you're looking at 150'. At 70F indoors/+5F outdoors that's a heat loss of U0.5 x 150' x (70F-5F)= ~5000 BTU/hr in the kitchen just from the sliders alone, even before factoring in the air-leakage (which is considerable with most sliders.) If it's single-pane glass it's about twice that. Replacing half of that slider-area with 2x4 R13 + R5 foam would cut that heat load down by nearly half, since the U-factor of that (MA code-min) wall stackup is about U0.067, an order of magnitude lower than U0.5 slider.

Every 10,000BTU/hr you can take of the heat load takes about a ton off the size of your ductless. Unlike the heat pump a reduced-ton has no operating cost and has a lifecycle 3-10x as long as a heat pump, and is worth spending more money on.

Without a room-by-room heat load calculation there's no way to say for sure what the good/better/best space heating options are. If you have a "K-factor" stamped on the oil billing from a mid to late winter fill on regular fill-up service that's enough information to estimate the whole-house load at it's current state of air-sealing & insulation, but won't tell us the room-by-room loads. A simple I=B=R approach to the heat load calculations is good enough for the relative sizing, but vetting the whole house load against fuel use would be important too. From there you can better estimate the "after" picture of your tightened up and better insulated condition.

Odds are pretty good that your basement leaks air like a sieve (most do) , and even the finished section isn't likely to be insulated well or properly, and is likely to be a large fraction of the heat load despite not being intentionally heated. With the oil boiler down there the standby & distribution losses of the heating system probably keep it reasonably comfortable, but that will not be the case once you're heating solely with ductless + wood-burner. It's a project, but air sealing & insulating the basement should be on the list and given some priority, even if it's beyond what was recommended by your MassSave auditor.

With an insulated foundation and a basement zone heated by a 3/4 ton mini-split (or a multi-split head) with a you can do significantly better on operating costs with a heat pump hot water heater than with the tankless coil in the oil-boiler. With a heat pump water heater if you continued to heat with the boiler (and no ductless in the basement), you can lower the minimum-temp of the boiler (or cold-start it, if the model is tolerant of cold starting) to reduce it's standby losses, since it no longer has to be kept at temp just for serving hot water, and it can be turned off during the summer. Despite early-model design & manufacturing issues, the 50 gallon GeoSpring is probably enough water heater for most 3-4 households, especially if showering rather than tub-bathing. A decent-sized drainwater heat recovery heat exchanger can extend the capacity of any tank by more than half for showering, but does nothing for tub fills.

Answered by Dana Dorsett
Posted Mon, 03/24/2014 - 14:11
Edited Mon, 03/24/2014 - 14:15.

Helpful? 0

BTW: Unless a window is totally shot and can't be reasonably repaired, it's usually a better bang/buck to add a tight low-E storm window. Harvey TruChannel storms are the tightest in the industry and they have a hard-coat low-E glazing option, but the Larsons sold through the big box chains aren't bad at all if you upgrade to the "silver" or "gold" series (the "bronze" are a bit leaky- you're better off with the tighter better-built units.). When used over a wood-framed single-pane double hung the performance is comparable to or slightly better than a code-min replacement window, at about half to 2/3 the installed cost of the replacement window. Over a clear-glass double pane performance ducks below U0.30.

Answered by Dana Dorsett
Posted Mon, 03/24/2014 - 14:22

Helpful? 0

Wow Dana! Thanks for all of that information, I have only had three fillups there as we just moved into the house in late December, but at $3.75/gal that is about $825+ per fill up. I would look at installing whatever I need to install by next winter to save on the cost of using the oil.

I will look on my oil bill for my K-factor, and see if it's there. Even though the 3 walls of sliders are nice in the sunroom, it is a heating nightmare, so we will probably take all but one wall of sliders out, replace with 2x4 walls, insulated, and then replace the left over slider wall with more efficient ones.

As for the pellet stove, the chimney is not on an exterior wall, it goes through my garage, and yes, I would buy 3-4 tons of pellets in the summer and store them, as I heard about the pellet shortage. Cord wood and pellets are pretty close in price in my area, and I was origianlly looking at a wood insert but researched that is has to be cleaned more frequently, and then I have to keep the wood outside, protected out of the elements.

What would you say are the next steps I shoudl take in trying to figure out what is my best, most efficient, cost effective option for heating my home?

Again, I thank you for taking the time to help answer my questions.

Answered by Khouri Rice
Posted Mon, 03/24/2014 - 14:29

Helpful? 0

It all starts with the heat load calculations based on the construction as-is. From there you'll have a better shot of figuring out what it/isn't cost effective for heating system solutions, and what's cost effective from building-envelope upgrades.

Sliders inherently leak more air, have twice the glass open-able door area than swinging doors, so if you're re-doing that section of wall consider going with a 6-7' double-door rather than a 6-7' slider. A swinging double-door gives you an opening big enough to drive a Prius through, for the same amount of glazed area, and are easier to reliably weatherstrip. (And note, to meet code min with a 2x4 wall you can't forget the "+5", of continuous insulating sheathing as a thermal break on the framing. There are other ways to get there if it has to match the prior framed wall thickness exactly, but we can go over that when the time comes.)

When all else is equal, the building upgrade wins, since it has a longer lifecycle and adds more comfort, and is protected from energy price volatility.

Looking at the utility service maps it appears National Grid is both the gas & electricity provider in Topsfield:

It's worth looking at their "Deep Energy Retrofit" rebate program for going better-than-code on more serious envelope-upgrades (including foundation insulation.)

Under this program you can get far deeper subsidy than the more general MassSave approach, but it requires a substantial project. But if you're looking at things like multi-ton ductless you probably have the right mind-set for tackling the building envelope upgrades at a more serious level.

I was involved with a DER on a 3-family in Worcester a couple of years ago that ended up getting more than $40K in subsidy from that program, but it was pretty much a full-gut rehab, and unoccupied during the renovation. That house is heated & cooled with one ductless head per floor (three separate mini-splits.) But it also had 3.5-4" of rigid foam insulation on the exterior of insulated 2x4 walls, and 6" of rigid foam above the roof deck. (Most of the rigid foam was reclaimed roofing foam from commercial demolitions, sourced through one of several vendors operating in MA, at a cost less than 1/3 that of virgin stock.)

Answered by Dana Dorsett
Posted Mon, 03/24/2014 - 15:02

Helpful? 0

If there is no K-factor stamped, the exact fill dates of the last three fill-ups, and the volume of the past two would be sufficient. With that information we can look up the heating-degree days covering the span of the past two fill-ups from a nearby weather station on, then work the simple arithmetice on the fuel use/HDD and the boiler's steady-state efficiency to come up with a BTU/degree-day number, and convert that to BTU/hr @ +5F (or any other outdoor temp) from a presumed heating/cooling balance point of 65F (which is close enough for these purposes.)

Answered by Dana Dorsett
Posted Mon, 03/24/2014 - 15:07

Helpful? 0

Dana, I will pull together thos enumbers and get back to you. Is it ok to ask for you email address or should I email you here? What do you do for work? Are you local (MA?)

Answered by Khouri Rice
Posted Mon, 03/24/2014 - 15:11

Helpful? 0

I am indeed local in MA, and work as an electrical engineer (electronic design, not power-grid stuff). The building-science/HVAC/energy-efficiency is currently just a hobby that I indulge in primarily with/for friends & family, though with the right business model I could probably make a living at it. ( I know at least enough to be DANGEROUS! :-) )

Reducing both operating cost & atmospheric-carbon output cost-effectively without ruining the house is part of the motivation for chasing these issues on blogs & web forums- the more people who figure out how to get there with reduced rather than increased financial stress, the more people will be doing it. Every existing house is a work in progress, and more difficult/expensive to make low-carb -low operating cost than with new construction. Something like 80% of the houses that will still be around in 2050 have already been built, so figuring out least-cost best bang/buck upgrade paths is important if we're going to be able to make a big enough dent in it to matter. Sketching out some of the details on projects like yours in an open forum also serves as a vehicle for pointing out how others can get there too. (If yours was the only 1960s 2x4 framed Cape in New England heated with an oversized oil-fired boiler that might not be the case, but I'm pretty sure there are more than just a few of those around, eh? :-) )

The recent-years high cost of heating oil & propane make the numbers for building upgrades work more favorably than they did 15 years ago with buck-fifty/gallon oil. If you can get the total heat load under 30,000BTU/hr ductless options start to look really really cheap, and in the long term the better-grade building envelope beats bigger more expensive mechanical system. In retrofit situations there's a big fuzzy middle ground, a middle ground easily skewed by subsidies, etc.

BTW: Have you seen this short readable RMI policy piece published about a year ago?

There is a MassSave subsidy of ~$500 for mini-splits that hit high enough HSPF & SEER numbers (primarily for the grid benefit of lowered peak summertime cooling power). Efficiency Vermont has even richer subsidies on a per-ton basis for up to two units for those heating with oil or propane, but only from a select list of higher-efficiency cold-climate versions (and of which would be appropriated in Topsfield): While I'm not expecting it to happen any time soon, that would be a very good policy decision for MA as well, given the huge amount of cash leaving the state annually for heating oil. Expanding the 30% federal tax credit available for ground source heat pumps to include highest efficiency ductless (which operates at comparable efficiency) would be good policy too, but it's been less than a decade since mini-splits have improved to that level, and not all really cut it in this climate the way the Efficiency Vermont short-list does. The recently release Mitsubishi M-series cold-climate units do though, and I expect Efficiency Vermont to have at least some of those listed going forward. (The MSZ-FHxxNA single-head units are 15-20% more efficient than any of those currently listed.)

Answered by Dana Dorsett
Posted Mon, 03/24/2014 - 16:32

Helpful? 0

Dana, "we" will look up... You got a mouse in your pocket?
Winter is done for as of this week we command....

Aj & his mouse

Answered by aj builder, Upstate NY Zone 6a
Posted Mon, 03/24/2014 - 16:40

Helpful? 0

One thing that might help what you hinted might be short-cycling
in the oil heat is to set the anticipator on the thermostat to a
longer cycle time. It might also be called "spread". Without
knowing what kind of 'stat you have I can't be more specific, but
if it's convincing itself to shut off sooner than it should there
might be a way to adjust its view of the world and let room heat
come up a little higher.

You probably can't go wrong with minisplits, and get nice efficient
A/C as well for the times it's needed. The wikkid-expensive route
would be some sort of heat-pump driven hot water system like
Daikin Altherma which could adapt to your existing baseboards,
but judiciously placed minisplit heads and a cozy fire downstairs
might be the better way to go. I live in your general neck of
the woods in a similarly provisioned neighborhood, no gas, and
it was great to be able to chuck pieces of the rusty old oil
furnace into the backyard knowing that its zero-combustion
replacement would be so much better, safer, quieter, etc etc.

The usual DHW solution for non-gasified houses is electric; I've
been pretty happy with my Rheem Marathon even if it's not the
latest spiffy heat-pump-driven thing.

The MassSave folks might be useful if you were confident they could
attack your basement with sprayfoam or dump more fluffy stuff in
the attic and the like if you'd rather not DIY, but reports from
the field seem to be mixed concerning the subcontractors they
hire out to do the work.

And I agree with what everyone else says about that big slider;
looking at it with an IR imager would probably make most of us cry.


Answered by Hobbit _
Posted Mon, 03/24/2014 - 19:11

Helpful? 0

It's unlkely that the Altherma can deliver the heat at baseboards designed for 160-180 boiler water (typically necessary to keep from destroying the oil boiler with condensation), but if there is enough baseboard, maybe.

The output (and efficiency) of the Daikin Altherma with 140F output is pretty abyssmal at 5F outdoor temps- the only way to really run them efficiently in New England is in low-temp radiant slabs or above-the-subfloor tubing radiant floor, and keeping the loads to well under 10 BTU/hr per square foot of radiant floor, and you can run with output temps at 90F or less most (or all) of the time.

Mini-splits or even a 4-6 ton multi-split would be more affordable than the low-temp radiation + Altherma solution. The Altherma is sometime a great retrofit into smaller or higher-R houses currently heated with radiant slabs & oil or propane boilers though.

Answered by Dana Dorsett
Posted Tue, 03/25/2014 - 15:36
Edited Tue, 03/25/2014 - 15:37.

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