Direct-fired oil hot water heater vs heat pump?

tmoney4688

Hi everyone, we have an existing direct-fired oil hot water heater that developed a pinhole leak on the top last night, so we've arrived at the situation of either replacing with another direct fired oil hot water heater, or installing a heat pump / electric water heater.
I've read through some older posts and I'm now leaning towards another direct fired water heater, namely for the fact that our basement can get pretty cold in the winter (high 40s).
Our current water heater lasted less than 5 years, should be still under warranty but the company is on holiday until mid next month (July), so not sure where that leaves us.
Anything else to consider? We have a newer oil furnace that we dont use much now, as we use our wood pellet stove to heat most of our house in the winter. Oil is really all we're able to get out here in central MA, and I dont think I want to hassle with propane at all.

Jamie Hall

Do you prefer cake or Sunday afternoon? Heat pump water heaters and oil fired directs are two very different beasts, and weighing the options is not simple. Full disclosure here: I have two houses with direct fired oil hot water I care for, and one house with a heat pump hot water heater.

Since you already have oil, that's not an issue.

OK. Oil fired hot water heaters are sometimes regarded as relatively inefficient in the use of oil (fossil fuel). But, in the northeast where you are, it's a toss-up, as so much of your electricity is generated by fossil fuel -- at a much lower efficiency. Further, in some parts of the country oil fired is more expensive to run -- but again, not where you are. Again it's a toss-up.

The advantage of oil fired direct is the insanely fast recovery which they provide. 50 to60 gallons per hour is not unreasonable to expect -- so while you can run out of hot water, it's not easy. Also, they are smaller. Heat pump hot water heaters, on the other hand, are much slower, so you need to be rather careful about your hot water draw, particularly if you want to stay with the heat pump operation and not engage the resistance backup elements.

The house I have with a heat pump hot water heater does well. It is an 80 gallon unit -- but there are only two bathrooms, and one elderly occupant, who finds that they do have adequate hot water. One of the oil fired units is in a similar house, but the other, a 32 gallon unit, is in a house with four occupants and three baths -- and all four occupants are outside working people, so at the end of the day there can easily be three showers running at once. It never runs out.

ethicalpaul

> much of your electricity is generated by fossil fuel -- at a much lower efficiency

Arguable, to say the least. But let's say that's true. The electricity that gets to your house is what you pay for, and that electricity heats the water in a heat pump water heater at something like 300% efficiency.

I don't know how they perform in the upper 40s (my basement has a steam boiler in it so it stays in the 60s) but I would think pretty well since even older technology outdoor heat pumps do fine in the upper 40s.

Jamie's single elderly resident's heat pump water heater is vastly oversized in my estimation. I'm in a two family household with a 50 gallon Rheem that only uses the heat pump to heat the water. If a family needs occasional high volume, there is a heating element in it to provide faster recovery at 100% efficiency instead of 300%+

Jamie Hall

Just remember, @ethicalpaul , that the relative efficiency -- and cost -- of electricity vs. direct fossil fuel power is widely variable with region and season. I was addressing central Massachusetts, where the OP said they were located, specifically. At more than $.30 per KWh for electricity, vs.around $3 for oil, one has to do the sums rather carefully... and in the winter, most of our power in this area is from oil or natural gas fired generation.

WMno57

tmoney4688 said:

Our current water heater lasted less than 5 years, should be still under warranty but the company is on holiday until mid next month (July), so not sure where that leaves us.

You could get a cheap electric resistance 40 gal water from a big box store to tide you over for a couple of months. I have one of these and it works great for me. I don't use large quantities of hot water.

Larry Weingarten

Hi, Two more things to consider are equipment complexity and durability. I prefer simple as it usually holds up better. About durability, we should get to the bottom of why your tank failed at under five years. Are there water quality problems... pressure issues... a leaky fitting on top?

And a third thing to consider is how water efficient can you make your plumbing system? The less structural waste you have, the less water will need to be heated. If you have to wait a long time for hot water to arrive, that's structural waste. If you have an eight gpm showerhead, that's easy to fix structural waste. Looking in this area could allow you to get by easily on the slower output of a heat pump, or let you put in a smaller tank.

Yours, Larry

Hot_water_fan

Pros and cons to both! Any idea how much oil you use every year for DHW? For some households, it works out to $10/month and efficiency (or inefficiency) doesn’t matter much versus install cost. For others, efficiency can be a better proposition. I personally like the pairing of a cheap, inefficient heater with a drain water heat recovery pipe for houses that use showers predominantly. That gets you solid energy reduction without the complications of higher end tank heaters. 

 

hot_rod

There is a federal tax credit on HP water heaters, and  local utility programs in many areas

Rheem has a incentive locater at their site 

here is what it looks like in my area

https://www.rheem.com/rebate-center/?ecr_rebateConsumerTypes=residential&zip=84020&searchTerm=Heat+pump+water+heater&ecr_product_type=solarwaterheater%2Cwaterheater