Oil to Electric Conversion

RadiatorRanger

Hi People -

I’m acquainted with an ~3200sf house, near Kenmore, Wa., built in 1964 that used oil heating with supplemental wood & electric baseboard in basement until late fall of 2019. The house has improved windows, doors, insulation and siding. There is a new electric hot water heater and a 200amp panel. Apparently this was a Better Homes & Gardens design.

The boiler is in the daylight basement. There were originally 2 zones; the basement zone hasn’t warmed for dozens of years, the Main and Upper Floors were mostly, comfortably warmed with hydronic, baseboard.

Over the years I’ve removed air while visiting. I don’t remember the radiators ever being particularly hot. Sometimes I heard clicking which I assumed was expansion and sometimes I could hear water flow/ dripping sounds from the system.

Getting gas to the site is expensive, i.e. < 20k. Oil has worked well but it isn’t ideal for reasons.

The three recommen










The recommendations are:
1) Go with a 7 head mini split - abandon existing system
2) Replace the oil boiler with same - retain existing system entirely
3) Install an electric boiler - retain existing with minimal repiping

I’m inclined to retain the existing system and install an electric boiler.

Some questions:

Does anyone have experience converting this kind of system from oil to electricity? I’m interested to hear how that went.

How about incorporating an air to water heat pump to this type of system when converting to an electric, cast iron boiler?

I was told (as I understand it) that b/c the type of system was typically installed in a loop with the emitters closest to the boiler smaller, and furthest from the boiler emitters are longer and that the radiators themselves are designed with high(er) mass than is optimal / functional for an air to water heat pump. How can this be confirmed?

Whats the best way to clean these emitters - compressed air?

I’m including images of the radiators, the boiler and a mostly accurate floor plan.

Your thoughts?

Thank You Warmly,
Radiator Ranger

STEVEusaPA

First you'll need a properly sized boiler either way. And based on the improvements made, probably much smaller, btu wise.
So first is a proper heat loss.
Next, you'll need to compare btu cost to dollars for oil vs. electric (and maybe even propane).
A properly sized/piped/installed modern oil boiler, with modern circulators and control, would be very efficient, burn very clean, and with proper maintenance would be extremely reliable.
You don't say why you wouldn't want to keep the oil.
If electric rates are low enough, electric boiler, but there are some other considerations with electric.

You could use compressed air (low psi) and a vacuum to blow them out.

RadiatorRanger

Hi -

Why move away from oil?
1) The access road appears to be failing and less load on the road is better.
2) In nearby Seattle there is an initiative to tax home heating fuel to induce a move away from carbon emissions (depending on how that electricity is generated).
3) Electricity is 'always available' unless the grid is down; no deliveries necessary.

Thanks

pecmsg

Where is Electric cheaper then Oil?

Jamie Hall

Check your electricity rates vs. the cost of oil very very carefully, and do not assume that the electric rates will stay low. They won't, with Seattle pushing for more and more electric usage.

Second, check your electrical service. If you are reasonably close to the same BTUh load, you will need 140 of those 200 amps to heat the house (I assume you have the normal 120/240 single phase power); there may not be enough left for other uses.

Third, do your heat loss calculations. They are essential. If you do them room by room -- as you should -- you can also determine whether or not the existing emitters are adequate. If they are, or are more than adequate, any imbalance can be corrected (though perhaps, if it is a series plumbed system, not without some difficulty).

I would say that oil is no less "always available" than electricity -- in fact, I would say it is more reliable, as one can generate power on site if need be to run an oil boiler. In the Seattle area, for political reasons, that may not be true. Also, electric power in the Seattle area is more "green" -- but only if one chooses to forget that Seattle is still connected to the national grid, which is far less efficient in terms of CO2 created to heat in the house than oil heat. That, too, however, is a political or virtue signaling decision, not an engineering one.

And may I suggest that if the subbase of the road is inadequate to support oil trucks it is also inadequate to support anything bigger than a small car for any length of time; there is a very real problem which has nothing to do with heat.

rick in Alaska

pecmsg said:

Where is Electric cheaper then Oil?

Most likely the Seattle area. Pacific northwest is usually pretty cheap for power. When I left eastern Washington, I was paying 3.5 cents per kw. I think it is around 9 now. My current rate here in Alaska is about 26 cents. Electric is out. However, I did just do an oil to electric conversion on a 3 car garage because the owner assured me it was cheaper, against my advice. She only ran it one month before shutting it down. I tried...
Anyway, if you just Google "fuel cost comparison", you can find sites where you can plug in numbers for different types of fuel, and it will give you costs per btu for each. Electricity might be cheaper there.
Also, if you can, keep those baseboards. They are cast iron and put out a nice amount of radiant heat. You probably need to run cleaner through them though. If you are not getting good heat out of them, it might be just because the boiler output is set too low. Either way, at the minimum get a newer boiler.
Rick

Canucker

> @pecmsg said:
> Where is Electric cheaper then Oil?

I can't speak for the States but I bet Quebec is cheaper to run electric than oil. Haven't done a comparison, just a hunch

pecmsg

Near Niagara Falls or Hydro dams I can see it. The other 99% on North America I don't see it.

pecmsg

Let me rephrase
Heat pumps all Elec yes under certain ambient conditions
All other times
Oil
NG
even LP
Will be cheaper to operate

DZoro

Plug your electric and oil numbers in this chart.

ethicalpaul

Possibly dumb opinion from an opinionated homeowner:

As much as I dislike oil, I would take oil any day of the week over resistive electric heating. What a waste.

But in that climate, I would run (not walk) to heat pump technology (mini split or otherwise). So cheap, quiet and clean, plus you get an AC install for free. How hard is that to sell??

I welcome correcting information on this opinion of mine.

Jamie Hall

No, I agree with you @ethicalpaul . Just don't sell it as green, because it isn't, unless you are off grid and generating your own power locally with true, undamaging renewables...

ChicagoCooperator

Why not heat pump to the existing system - ground source? No minisplits for ac though.

stretch5881

I'm not a tech, but have some experience here. My dad needed to replace his oil fed boiler around 10 years ago. He decided to go through his electric coop and get an electric boiler instead. They talked him into it with all electric rebates and less maint. The house was new construction in 1988 and about the same size as yours. 4 heat zones. They added a separate line, meter and breaker box for it.
About 3 days a week they shut him down for a couple hours for load management.
He passed away in November and I have the heat turned down to 65 on the main floor and 60 on the other floors. The house and appliances are not being used. No lights are left on. Just the yard lights, boiler and water heater are operating.
Here is the last bill.

rick in Alaska

stretch5881 said:

I'm not a tech, but have some experience here. My dad needed to replace his oil fed boiler around 10 years ago. He decided to go through his electric coop and get an electric boiler instead. They talked him into it with all electric rebates and less maint. The house was new construction in 1988 and about the same size as yours. 4 heat zones. They added a separate line, meter and breaker box for it.
About 3 days a week they shut him down for a couple hours for load management.
He passed away in November and I have the heat turned down to 65 on the main floor and 60 on the other floors. The house and appliances are not being used. No lights are left on. Just the yard lights, boiler and water heater are operating.
Here is the last bill.

So how big is this place, and is it insulated? That seems like a lot of power. On the plus side, it looks like you are paying an effective rate of only about 11 cents, which seems pretty great.
Rick

stretch5881

About 3500sf stick built in 1988. Insulated as well as they did back then. Even the basement walls have styrofoam beads in the block.

Icarus

Radiator Ranger,

I am currently consulting on a project in Bellingham to convert a nat gas fire conventional boiler to run off of air to water heat pump system. I suggest you PM me or info, (not trolling for work) and I can send you some info.

The bottom line, heat pump hot water coupled to your boiler is a no brainer in the PAC. NW, especially if you can tie it to roof top solar, both from a $$ equation as well as an environmental equation. One of the big questions to answer is if you can keep you house warm with ~120f water in the rads or if you need it to be warmer. (Relying on the boiler techs in this case is, I have found to be, useless). If you can keep your house warm at 120f your options are greater. You can send me a note, Icarus dot consult at Gmail dot com.

Icarus

hot_rod

I too would run a load calc see if an air to water heat pump would work. If you have enough convector to operate in their sweet spot.

Assuming you don’t need AC

Got room for PV to offset some load?

Could be some rebates for going electric dsire.org is the place to look

Could be both PV and heat pump monies available?

Icarus

Conventional heat pump will put out water at a max of ~120f. A Sanden CO2 heat pump will put out hats water in excess of ~160f. The issue with my client is regardless of the btu capacity, are the emitters big enough to keep the house warm at ~120f.

Icarus

hot_rod

SoMe test data here. You need to consider weather data also, how often are you at design condition needing the high operating temperature?
Sanden claims 176F. Operating down to -20F. But watch COP at low ambient

You need to crunch all the numbers, SWT required, energy cost, current heat emitters, etc. There is no one answer fits all

https://neea.org/img/documents/NEEA-Emerging-Technology-Report-Q4-2018.pdf

Icarus

The compromise that we have come up with for the Bellingham project is not to design for the worst case (lowest overnight/highest wind cases) but to design to produce ~90%+ of the heat load 90% of the time. We will augment the shortfall when needed with a conventional minisplit, which will have the added benefit of supplying a modicum of A/C in the summer in the sleeping areas. We also need to add additional heat emitters of some sort in two downstairs rooms, and the minisplit solves that.

We did a beta test the past January where we had outside temps ~15f,with a 10 mph wind. We ran the current boiler up to 120f, then shut it down until the radiators dropped to 110f, then we repeated. Over a 3 hours period we were able to raise the net temp of the entire house (1890’s victorian) 5 degrees F. The calculated BTU load in that experiment was ~20k/hour. Knowing the Sanden only produces 15k, it would be short for both CE and DHW in this case...but most of the year it would be fine, hence the supplement with the minisplit. In this case they also have a high ef wood stove currently to augment, but the minisplit would do as well.

The net/net of it is that that Sanden will deliver the DHW, and most of the CE for most of the year. The net cost of both the Sanden and a dual zone minisplit is not too far out of line of a conventional boiler change out.

Icarus

PRR

DZoro said:

Plug your electric and oil numbers in this chart.

Thanks!

But it violates my un-checked assumptions. I entered recent prices and my last and current burner %s. I had figured, when I converted from oil to propane, the improved efficiency did not quite make up for the higher $/BTU. However the spreadsheet says I am paying a buck less for propane. And this agrees with my unaudited impression of the checks I write.

Fuel Oil $2.66 72% = $26.64 (recent quote) (old furnace)
Electric $0.17 98% = $50.84 (last bill)
---- Air Heat pump = $34.69 (works in Maine??)
NatGas (N/A) 96% = $10.42 @ $1
Propane $2.15 94% = $25.05 (this winter verbal contract)

Notes: the oil burner claimed 80% but was in sad shape and blowing much heat up the stack; the 94.5% propane stack is not warm. I know they can demo a (reasonable price) heatpump in Maine air, but reports are they don't last. I am 30 miles of rock away from piped-gas. While my price for propane is not in writing, and varies year to year, he has never raised the October price even when propane shortages make headlines.

Jamie Hall

@PRR 's comment sort of confirms what I have thought -- that oil and propane are reasonably competitive in our area -- and that with our climate and electrical rates nothing else is, except in urban areas where natural gas is available. Thank you for the information!

Icarus

Heat pump in Maine actually works pretty well, most of the time. AS for my previous comment about considering a Sanden for our Bellingham project, we are rethinking that and are now considering a air-water Heat pump, coupled to the existing radiator system, as well as adding a couple of fan coils that would provide heat and cooling. In some ways not as elegant as the Sanden but has a higher capacity and a better over all sea salon heating COP. It also contains “normal” components including Mitsubishi compressor, name pumps and heat exchangers. This will do 100% heat, 100% DHW and 100% AC in one relatively simple installation, no refridgerant tech needed, only water piping. The Chiltrix system also has an add on “smart” heating element to efficiently boost the hot water temp in the heating loop if needed to make up for a short fall on those exceptional design (cold) days. The hot water heater system offered also has a built in boost element mostly to boost tank temps once a week to over 140F to prevent legionella.

Assuming Seattle City light power prices are near that of Puget Power (actually I think they are a bit lower) the KWH rate is ~$.10-.13kwh. Add in some roof top solar and you can begin to heat (and cool) nearly (if not free). Same in Maine. My sons Maine solar array, similar in size to mine in Bellingham outperforms mine by a long shot in the winter. Summer we will be very close...he hasn’t been up for a summer yet.

Icarus

Robert O'Brien

> @RadiatorRanger said:
> Hi -
>
> Why move away from oil?
> 1) The access road appears to be failing and less load on the road is better.
> 2) In nearby Seattle there is an initiative to tax home heating fuel to induce a move away from carbon emissions (depending on how that electricity is generated).
> 3) Electricity is 'always available' unless the grid is down; no deliveries necessary.
>
> Thanks

Bioheat has very good availability in the Pacific NW and is exempt from the Seattle heating oil tax .

Jamie Hall

Bottom line: there are situations where any given energy source, and any given way to heat a building, works, and there are situations where it doesn't. The job of a competent engineer or installer is to pick the best one for the situation, not sell any particular one -- or point of view. That's the difference between an engineer or craftsperson and a salesman.

Solid_Fuel_Man

Exactly as @Jamie Hall said.

Regional prices are much different for different fuel sources. Propane is about the least expensive fuel where I am. Aside from wood, which is half the cost again.

mikeg2015

stretch5881 said:

About 3500sf stick built in 1988. Insulated as well as they did back then. Even the basement walls have styrofoam beads in the block.

That loooks about right. I had a home from 1993, 2500sqft in SW Michigan. $150 natural gas bill in winter. Gas vs electric is around 3:1 in cost depending on rates of each.

Around my area, which is mostly rural outside of a few smaller towns (1-8k people) everyone uses propane. Electric rates are very high here in our corner of Iowa, so propane I honk runs about 1/3 the cost per BTU if you prepurchase it in the summer. Natural gas is around 1/4.

I;m on natural gas and only use my heat pumps above 50F because 20-65k BTU 2 stage zoned heat pumps running 70-80% of the time heat more evenly than a 160k output boiler running about 10-20% of the time.

DZoro

A combination boiler and heat pump working together, is a great system. You can set the heat pump to operate during mild weather, and your gas or oil can take over during the colder times.
D

Zman

pecmsg said:

Let me rephrase
Heat pumps all Elec yes under certain ambient conditions
All other times
Oil
NG
even LP
Will be cheaper to operate

This is a silly generalization.
It all comes down to local pricing.
Where I am propane usually the same as electric. Natural gas is 1/3rd to 1/5th the price of either. Fuel oil does not exist.

If you design the system for low temp hydronics, you can switch to whatever fuel source is most economical in the future.