Is my "standby" Fuel Oil consumption high ???

Leonard

Have hour meters on burner and circulator. Finally been warm lately so I can get a handle on standby losses, FHW circulator hasn't run for 3 days. So burner is only supplying standby losses and domestic HW. Tankless DHW coil in furnace water jacket

My hour meter on burner has been averaging 0.9 hour/24 hours. 1.1 GPH nossel, so 1.0 gal/24 hours. Does that sound high?

Only two ~ 10 minutes showers per day, and quick handwashing ( two 60 year olds). Old pre 1.1GPM shower heads, 40 psi water. Without old waterpik shower head attached to shower spout flow is ~ 3 GPM on cold water , less on hot (boiler has 5 GPM orfice) Cold water input is 42 deg F.



60 year old National Sunray IV , boiler # 5-19A/O/OP , rated 128k BTU/hr 1.6 gal/hr
Has original burner, National -US model NB2-K2, firing rate .85-2.0 gal/hr, nozzle = 1.10/ 80 deg/ B

Chimney is ~ 4 stories from cellar floor to top. No motorized damper for when burner is off, has barometric damper.

Jamie Hall

Does sound a bit high. Your showers are using a total of about 400 to 500 pounds of water, with a 60 degree temperature rise -- which works out to only 24,000 to 29,000 BTU. 1 gallon of oil is around 140K BTU... even if your boiler is only 50% efficient (which is quite possible at that age!) that's still about 70K BTU. Hard to say where the rest is going -- unless it is, as you surmise, standby losses.

Leonard

I'm assuming chimney is the dominant loss, no motorized damper

STEVEusaPA

Jacket loss, piping losses, an old large water content boiler. Sounds about right.

GBart

60 year old National Sunray IV ??????????

seriously? you're worried about efficiency with a 60 year old system?

it's 2018, buy a System 2000, zero standby loss

GBart

at the very least get a outdoor reset control

Solid_Fuel_Man

A gallon a day with domestic coil is about right. I bet less than 25% of the BTUs get the the DHW in the summer.

GBart

System 2000, no standby loss, mine runs 2 10 min cycles in the summer for h/w, I burn about 1/4 gal a day from May through October

ChasMan

Sounds right to me, I used to use 200 gallons easy over the summer on tankless. A new setup will pay for itself easy. You just have to buy it right and not pay some shmuck oodles of dollars to botch your install for you. That is much harder than it should be, that I can tell you. Try the find a pro link.

Solid_Fuel_Man

I like using solar imdirects. Has a coil so the boiler males the hot water during the heating season, and an electric element so you can turn off the boiler completly during the summer. This does not work well with old boilers though, as most leak when they actually cool down.

Leonard

As I took a shower last night I measured shower flow for 1 minute with a plastic bucket...was 3 GPM. Immediately stuck my thermocouple in bucket, water was 101 deg F. February cold water is 42 degs so ~ 60 deg rise. And 88.5k BTU/hr heating rate, (tankless coil)

Assuming two 10 minutes showers /day that's ~ 29.5 kBTU /day.
You nailed it Jamie.

Not ready to change hardware yet, first want to see what I'm using, and learn some things first.

Turns out my OLD boiler pressure safty valve is leaking, so boiler may not be. Even though I heard it hissing from firebox when I ran out of oil couple years ago and boiler cooled to ~ 90 deg

Boiler is a nice quite 1800 rpm unit, unlike the new 3600 rpm ones.

Robert O'Brien

https://aceee.org/sites/default/files/pdf/conferences/hwf/2018/7b-butcher.pdf

STEVEusaPA

Boiler is a nice quite 1800 rpm unit, unlike the new 3600 rpm ones

1725...3450

Solid_Fuel_Man

This is where we get into what the actual efficiency of a tankless coil is.....its pathetically awful in the summer! Lots of standby loss, we affectionately call them chimney heaters!

Leonard

chimney heaters .... true enough. However I HATED running out of shower hot water in my 1-st apt. (electric hot water tank.)

That brings up another point, I did consider adding a motorized exhaust damper to limit chimney losses ( more for winter losses) . But since that might ultimately cool chimney I wonder if that would lead to more corrosive condensation in chimney and also cause reduced "draft" over fire problems. My chimney is ~ 9"x13" size red "tile" ~ 3 ft sections. ~ 4 stories from cellar floor to chimney top.

Jamie Hall

I would just quietly note... that an often overlooked option, if one is burning oil anyway, is an oil fired hot water heater. Efficiency isn't that great -- 85% on the one in the building Cedric lives in -- but not that horrible either. If the current one lasts 20 years I'll be real happy. However... that same building can, on occasion, have as many as 20 guests at once, with five full baths... and never runs out of hot water (believe me, as the super I'd know right away!)

Solid_Fuel_Man

I think a Bock direct fired oil water heater has a 65% real world efficiency. They will make copious amounts of hot water though. I grew up with a Bock in the basement. Lasted 24 years too. Replaced it with a used Bock I pulled out of a house that went propane. My parents are still using it.

I service a couple of kids summer camps. They both have like 10 showers all served by a single Bock.... but kids camp ain't the same as Jamie's place!

Jon_blaney

I have a Bock, 32 gallon, I get hot water and use for hydro-air heat in half my house. It is the standby loss that kills the efficiency on these things. Mine is about 15 years old. Water quality has a lot to do with how lone these things last.

STEVEusaPA

Jon_blaney said:

...Water quality has a lot to do with how lone these things last.

And maintenance. Most people never check/replace their sacrificial rods.

Solid_Fuel_Man

Yeah the 6" vertical flue with a short turbulator at the top makes for a lot of standby loss.