Any alternatives to oil for hi temp baseboard heat?

wlee

We're located in the Mid-Hudson region of New York state, with an approx 2000 sq ft raised ranch home that still has it's original Peerless oil boiler from when the home was built in 1967. I've been holding off replacing the boiler, hoping for someone to develop a central heating solution for older homes with fin-style baseboards that require higher temp water than conventional heat pumps can provide. Having gotten through another winter with minimal issues with my current system, I feel it's prudent to think about replacing it. I'm very reluctant to spend 5 figures on replacing it with another oil-burning unit, considering the current prices of heating oil. I had found some information online about Daikin and Nordic heat pumps, but these don't seem to be available locally - I actually phoned a company that was a Daikin dealer, but they had no air to hi temp water heat pump solution they could quote me. Is there any heat pump product available in my area that can serve as a "drop-in" replacement for an oil-fired boiler?

If not, and I have to continue with oil, the best answer seems to be to find a system that uses as little of it as possible (natural gas isn't available where I am, so any "gas" solution would need to be bottled propane). Buderus and the EK System 2000 seem to come up most often when searching for efficient oil boilers, and based on some of the discussions I've read on these forums, both are good units. Of course, I'm pretty sure anything I consider will be more efficient that what I have now: 55+ y/o Peerless oil boiler, 2 zones, with a third "zone" piped for an indirect hot water tank. I've also noticed that EK has a solar hot water product they offer. Does anyone have any experience with that?

Jamie Hall

If by high temperature you mean 160 or over. No. Some people seem to be working on it, rather sporadically and with varying degrees of success, but a generally commercially available unit? No, at least not yet.

The two products you mention are both excellent -- just keep in mind that it depends a lot on the skill of the installer, as much as the quality of the boiler.

hot_rod

Start here.
https://www.caleffi.com/sites/default/files/file/idronics_25_na.pdf

If there are times when you need 160F or higher temperature supplies to the fin tube, then no there is not yet a heat pump option.
However much of the year you may not need 160F supply. So the HP could supplement the oil boiler.

A room by room load calc, see how much fin tube you have and how them output changes with lower supply temperature.

Make the home as efficient as possible first. Upgrade insulation, air leaks, window coverings etc. A blower door test would help locate air leaks.

go to www.dsireusa.org for some programs to help with energy upgrades.

kcopp

How tight is your home? That is you best bet for starters. the most efficient system is one that runs less... find an energy rater that will do a blower door test on your home. They will find all the leaks and the places insulation can be added.

fentonc

It is worth it to characterize the heat loss from your house and the output of your baseboard - it doesn’t stop putting out heat at lower temperatures, it’s just less heat. It turns out my baseboard could probably heat my house with 110F water, and definitely with anything warmer than 120F, but I would probably run it constantly rather than blasting out heat at 160+F on a low duty cycle and using deep setbacks. Be sure to post here if you do find a place that installs A2W heat pumps - I saw an installer in fishkill (I think) that installs and supports Enertech Advantage A2W heat pumps, which are cold-climate rated and also support backup electric boilers for the handful of very cold days.

fentonc

This is the place: https://www.silvestrisons.com/webapp/p/2212/advantage-air-to-water-heat-pumps

pecmsg

fentonc said:

This is the place: https://www.silvestrisons.com/webapp/p/2212/advantage-air-to-water-heat-pumps

So, your equipment WILL give him the 180° water needed at design conditions?

Hot_water_fan

So, your equipment WILL give him the 180° water needed at design conditions?

We don’t know that 180 is required yet. Plus a hybrid situation would work!

In_New_England

I agree with folks here saying to do a heat loss calc. My current oil boiler is 140 MBH, but my radiators at 180F give out max 50 MBH.

According to my calculations, on design day (9F) my heat loss is 34 MBH, which can be served by 160F water.

What I would be wary of is betting the farm on this calculation: I would not go into a winter without some kind of back up before I knew it was working.

One suggestion: Could you lower the base board temp and see how well that works this winter? The boiler will cycle a lot, of course.

fentonc

@pecmsg - No, it will definitely not give 180F water (at least with that heat pump - the backup electric boiler might be able to), but hydronic heating systems are very frequently overdesigned, so it pays to do a proper heat loss calculation (or measurement based on previous fuel usage and temperature data). My house has a heat loss of like 24K BTU/hr at the 12F design temp based on actual measurements this last season, but it has 87K BTU/hr of baseboard and an 83% efficient cast iron boiler with 140K BTU/hr nominal input. At 120F my baseboard could still put out 30K BTU/hr, and we only had 3 days this last season close to the design temp - it would have added like $10 to my bill if I had turned on an electric boiler those days. I think the Enertech Advantage can go up to like 135F by itself, but whether or not it's appropriate depends on knowing the actual heating requirements, what the existing radiation is capable of (or if you upgrade it with higher output baseboard or panel radiators), and what the actual weather is like for your location.

wlee

Thanks everyone for your comments and suggestions. We've done a few updates (foam insulated boards behind new siding, double-pane replacement windows, new doors, etc) but the energy consult sounds like a good idea to identify other issues. Would they be able to do the heat loss calculation, or is that something the heating contractors should do? Pre-COVID, I had three different local companies come out to price a replacement boiler. I asked for a heat-loss calc from all three, and all three said it wasn't necessary, they had done hundreds of homes like mine and knew what was needed.

Robert_25

How much heating oil did you burn last season?

In_New_England

wlee said:

I asked for a heat-loss calc from all three, and all three said it wasn't necessary, they had done hundreds of homes like mine and knew what was needed.

If what everyone talks about is a theoretical heat-loss calc then I'm not surprised they would say this AND you can do this yourself with a variety of tools.

There's even the old X BTUs/sq ft rule of thumb that probably brings you within 20% of the real number which is sufficient for mod-con boilers and, probably, non-modulating boilers too.

I learned on these here forums that boiler cycling nor new-fangled boilers shortens their life, but "cycling" is an ill-defined term.

I do take to heart the "Don't over-size your boiler" advice.

You can, yourself, do the heat output calcs for your baseboard at different temps and get a good idea of how large a boiler you should get regardless of heat-loss.

My theoretical baseboard output is 120% of my theoretical heat loss, and this was done by an engineer (if at all) 60 years ago, probably using a rule of thumb. It seems to have worked.

wlee

@Robert_25 between Nov 19 and March 11 (date of last delivery), I used 335 gallons. Today the tank gauge is a bit under half, so add another 140-ish gallons? So about 475 gallons between Nov 19 and now.

fentonc

You can use this site to get your 'heating degree days' for your location: https://www.degreedays.net/ and that time period (it's probably more accurate if you can just do the oil consumption during some period in january-march if you have it, when you would have been consistently running your heat).

There are 138K BTUs in a gallon of oil, and your boiler has some rated efficiency (call it 80%). Then do:

Heat loss in BTU/HDD-hr = (Gallons of oil) x (138K BTUs/gallon) x (0.80 efficiency) / (heating-degree-days x 24 hrs/day)

Your location will have a 'design temperature', for which 99% of the time it will be warmer than that. If you take your indoor temperature (call it 65F, which is the standard used for heating degree days) and subtract your design temperature (mine is 12F, for instance)

(65F - 12F) = 53F x (Heat loss in BTU/HDD-hr) = BTU/hr of useful heat for your house on the worst day

Hot_water_fan

@wlee with DHW included, that usage implies a low heat loss, say 25,000 to 30,000 btu/hr. That's probably why no one has done a heat loss for you: the smallest oil boiler will be about 80,000 btu/hr, so guaranteed to be oversized. 

How many linear fear of baseboard do you have? 

jumper

Some places CNG is available. Truckload contains less energy but if one is close enough to vender and if you have room for trailer ......

wlee

@hot_rod that idronics paper exactly describes the issue I'm trying to resolve, thx for the link. I've only skimmed it so far but will take a closer read.
@Hot_water_fan approx 90 LF of fin-tube baseboard on the upper level zone, and 48 LF on the lower. Plus a third "zone" used for indirect hot water.

This brings up another question: during the summer, when the boiler is only used for hot water, does it need to be set at 180? Could I lower it to, say 140, and then bump it back up once we move into colder weather?

Robert_25

Hot_water_fan said:

@wlee with DHW included, that usage implies a low heat loss, say 25,000 to 30,000 btu/hr. That's probably why no one has done a heat loss for you: the smallest oil boiler will be about 80,000 btu/hr, so guaranteed to be oversized.

Agreed.

wlee said:

@hot_rod that idronics paper exactly describes the issue I'm trying to resolve, thx for the link. I've only skimmed it so far but will take a closer read.
@Hot_water_fan approx 90 LF of fin-tube baseboard on the upper level zone, and 48 LF on the lower. Plus a third "zone" used for indirect hot water.

This brings up another question: during the summer, when the boiler is only used for hot water, does it need to be set at 180? Could I lower it to, say 140, and then bump it back up once we move into colder weather?

138 LF of baseboard seems pretty generous for the load calculated based on fuel consumption. An air to water heat pump would probably do a fine job heating the house for most of the winter. You will need some type of backup heat source (oil boiler, electric resistance boiler, etc).

Your boiler definitely does not need to be at 180 degrees all the time. 140F is as low as you should go, and may or may not be enough to keep up with your domestic hot water demand.

fentonc

@wlee - your house sounds almost exactly like mine. Assuming you have 'typical' (2"x2", 55 fins/ft) baseboard that's ~550 BTU/ft-hr at 180F, your total house heat output with the following average supply water temperatures would be:

• @110F = 138' x (140 BTU/ft-hr) = 19,300 BTU/hr
  
• @120F = 138' x (190 BTU/ft-hr) = 26,220 BTU/hr
  
• @130F = 138' x (240 BTU/ft-hr) = 33,120 BTU/hr
  
• @140F = 138' x (290 BTU/ft-hr) = 40,020 BTU/hr