Toyotomi water heater

mark smith

maybe what you say is true ...

but No heating appliance should be making 500 ppm monoxide

Dirk Wright

Combustion analysis results

I have a Toyotomi oil fired tankless water heater. This heater can be direct vented or chimney vented. I have it connected to a 24 foot tall masonry chimney via a 5" flue of less than 4 feet. I have a 5" barometric damper installed near the breach, which is at the top of the heater and goes straight up for a foot and a half. I drilled a combustion test hole a few inches above the breach, and below the damper. With the heater running constantly in steady state, I got zero smoke and the following results:
CO 133ppm;
O2 6.9%;
Free air 199ppm;
Stack temp 596F;
Ambient temp 63.5F;
Eff. 79%;
C02 10.4%;
excess air 45.7%;
Draft -0.13wc;

Test instrument was a Bacharach Fyrite Pro 125. I had to connect a water hose to a laundry tub and run it outside and run the water continuously with the temperature on the water set to maximum (180F) to get it run long enough to achieve some kind of steady state. I didn't want to fill up the septic tank with hot water....

Also, the nozzle is a Delavan .85gph type del-o-flo A 60deg. The manufacturer's oem nozzle is a type XA, which is apparently only available in Japan or through dealers for $30. (!!!)

Any recommendations for improving efficiency? I am confused about the draft, since this flue is shared with an oil fired furnace, and the draft at the test hole for that is only about -0.02-> -0.04 wc. I can see that the draft for the water heater is too high, but the air supply to that burner is not adjustable. It's apparently intended for a direct vent arrangement because the fan is rather large. The pump pressue is adjustable, as is replacing the nozzle. I have not measured the pump pressure, but I assume it's the manufacturer's spec of 192psi. The manufacturer states that this water heater is supposed to be 88% efficient. I'm not getting that, obviously. They also state that flue gas temperature is supposed to be less than 500F, yet I have somewhat more than that. My opinion is that there is too much air flow through the burner, but that's just a guess. Any suggestions are appreciated.

mark smith

well, if ya want to get thier spec's

buy thier parts...

monoxide is somewhat high, not having experience with these i can't really say, but the Design nozzle will possibly lower monoxide and the firing rate

you seem to be slightly overfired

o2 maybe a tad high, but you won' have to clean it

Dirk Wright

No real specs available

Hi Mark, I have the service manual for this unit. I had to beg the distributor to let me buy it. There is no one within a really long way that I know of that even know what these things are, let alone be willing to fine tune one. It does heat water very fast.

Anyway, the service manually merely states that if a smoke test reveals zero smoke, then everything is fine. There are no specs for CO, excess air, etc. I ordered one of their expensive nozzles and will someday do a comparason test. (electrodes are $98 EACH! - though the service manager at the distributor said they rarely need to be replaced) I do not know what the difference between a type XA and a type A would be, though I can take the old nozzle apart and compare I suppose. This unit short cycles so quickly under normal conditions that I have to rig up a long hose to get it to run continuously.

I suppose the intention of these things could be to over fire them, since it has to heat the cold water as it's coming in. I mean, it has a 148,000 btu input, which is more than my furnace! That's a lot of btu's into a small 5 gallon heat exchanger. Do the gas and propane tankless water heaters also have a high btu input? They must I assume.

I had a .75 60 deg nozzle in there a while ago, and I went to change it recently to install a Protek check valve, and I noticed carbon on the end of the air tube assembly, like the spray was hitting near there and not clearing the head completely. I cleaned it up of course, and put a .85 del-o-flo in there. I didn't do any testing on the .75 though. I'm guessing that the type XA must have a different spray pattern than the type A. It must be more narrow or something. I am in contact with Delavan to try and understand what is special about this type XA nozzle, but they said no U.S. equivilent is known without combustion testing. So, I broke out the tester and now I'm testing...I'd like to just verify the manufacturer's claim of 88% efficiency but that seems unlikely. I just find it frustrating that they have not provided any air supply control that I can see. I presume that different draft situations call for different air settings, among other reasons.

Anyway, thanks for your help!

mark smith

think about how many Bute's are going into that cold water

a million Btu will heat 30 gpm.....

well, i wouldn't tinker too far, that is, unless you like cleaning oil appliances

you could cut the air back, ifn' yer Mister Anal...

don't go below, say 5% .. see which way the monoxide goes, thats your best indicator

maine rick

i sell and service these units. i've also been told the nozzles are made for toyotomi only. they make them in the US then ship them to japan they package them then ship them back to us at a high price. i would not mess with the nozzle my self. they are not a piece of cake to clean. had to do a few, not fun. also the pump presure is metric. they can be adjusted ,but not much it will affect the photo cell. also been there done that.if you find out anything please let me now.thanks
also watch the well that the thermister screws into they are very weak use a half turn with wrench them turn water on if on leaks leave it

Dirk Wright

Thanks!

Hi Ricky, thanks for your input! I took the original nozzle and took it apart and cleaned in my ultrasonic cleaner. Looks like new now. I suppose I should put it back in with a Protek check valve on it. The check valve made a big difference during start up. It used to be that I'd smell diesel fuel outside but no longer. Also, after a year or so, I'd get a puff of blue smoke out the chimney on start up. Also no longer hopefully. I'll probably take the protek and put it on the oem nozzle. The Japanese may be advanced in some ways, but they don't seem to have a solenoid valve for the pump like the Beckett Clean Cut pump. Mine's been very reliable otherwise.

Dirk Wright

Thanks

Thanks Mark, I'll try and rig up some kind of way to reduce the air flow and see what that does.

Dirk Wright

new combustion analyzer results

I changed the nozzle back to the original type XA with a new Protek check valve on it. I had taken this nozzle apart, cleaned it in an ultrasonic cleaner, inspected it and put it back together. It looks brand new inside and out. I managed to get the water heater into a steady state after a few minutes of running. These are the results:
CO: 282ppm;
O2: 8.6%;
Free Air: 479ppm;
stack temperature: 570F;
ambient: 61.8F;
efficiency: 79.6%;
CO2: 9.2%;
Excess Air: 64.7%;
Draft: -.07wc (fluctuated between -.04 and -.13);

I can see that the CO went way up, as did the free air and excess air. The O2 went up also. I don't think I'm getting good combustion with this nozzle, though the efficiency is about the same. Any suggestions?

mark smith

your monoxide is way to high at 500 ppm ...

your o2 has also gone up that leads us in the direction of Too much air ..


firing rate must be ok as the stack temp is under 600

Dirk Wright

yeah, no kidding

Hi Mark, I installed a .75 gph del-o-flo with the Protek check valve and ran it again:

CO: 249ppm;
O2: 9.6%;
air free: 461ppm;
stack: 534F;
ambient: 62.5F;
Eff: 78.1%;
CO2: 8.4%;
excess air: 78.6%;
draft: -0.05wc;

It obviously didn't help much going to a smaller nozzle. I can't adjust the air without stuff like duct tape or something.

I also have a warm air furnace connected to the same flue and chimney:

CO: 65ppm;
free air: 91ppm;
draft: -0.04;
O2: 6%;
Ambient: 61.8F;
Stack: 541F;
Eff: 81.3%;
CO2: 11.1%;
excess air: 37.3%;

Sure wish the water heater was even in the ball park of the furnace. I'm going to check the pump pressure in the water heater, since poor atomization could lead to some of this problem at least. I'm also going to run another test when I get the expensive oem nozzle in the mail. This water heater is just nuts!

Is it legal to use a regular hydronic boiler for domestic hot water? I have a friend that may be getting rid of his in year or so. Obviously, I'd need an antiscald valve with something like this.

Dirk Wright

I got it!!

I just went down stairs and took off the air intake cover and took a piece of cardboard and ran the water heater and the analyzer. I held the piece of cardboard over the opening to shut off some of the air. The best results were when it was covered about 3/4!! Way too much air! Thanks Mark!!

Here are the results:

CO: 124ppm (though I saw 99ppm at one point);

draft: -0.10wc;

O2: 4%;

air free: 153ppm;

ambient: 61.1F;

stack: 482F;

eff: 84.1% (yeah!);

CO2: 12.6%;

excess air: 21.9%;

So now I have to rig up some kind of device to close off the air flow. I just can't believe that the manufacturer is so lame about this! I shouldn't have to do all this experiementation!

Ray Landry

Your draft is kinda high do you have a barometric dampner? also your co2 is getting high as well, did you test for smoke?

maine rick

what you need to do ,is look in the owners book for the warrenty page find the phone number to toyo call them and ask for randy stone.he will help you .

Dirk Wright

Field Controls RC

Hi Ray, I have a 5" field controls barometric damper less than a foot from the breach. I have another one on the furnace. I think I'm supposed to have 6" dampers instead, since my chimney is higher than 15 feet. Oh well. It was a windy day yesterday, and the draft was constantly up and down. I did the smoke test before I started all this and got zero.

Dirk Wright

Thanks!

Hi Ricky, thanks! I'll give him a call. I hope he's not as snooty as the distributor.

Dirk Wright

more results

Hi Ray, I have some more numbers here. First, let me explain that this unit is set up for chimney use, meaning that there is a kind of "lid" over the air intake, the air intake is a 2" tube sticking out of the top of the box and the "lid" fits on top of it. The previous test was performed while I held a piece of cardboard over this hole with the lid removed. I took this "lid", which is like a 2" tube with an inverted large soup can over it and spaced such that air flows up and then back down into the box, and stuff foam into about 3/4 of it and secured the foam with aluminum tape. I re-installed the "lid" and ran another test and got these results:

CO: 98ppm;
draft: -0.12wc;
O2: 8.2%;
air free: 161ppm;
ambient: 64.9F;
stack: 503F;
eff: 80.7%;
CO2: 9.5%;
excess air: 59.9%.

Without a real way to fine tune the air supply, it is tough to fine tune the combustion. I think Toyotomi really screwed up with these units by not providing an adjustable air supply. I can't believe thier claim of 88% efficiency any more, and I'm just glad I was able to get the CO down so we don't poison ourselves.

Thanks again to everyone for the generous help with my water heater! I'll post more information as it becomes available, but I think I want to take a break from it today. It's just too frustrating!

Bruce M.

You are Overthinking This

I have a Toyotomi in my own house for about 2 years now. I have never had any need to test the eficiency because of the way the unit cycles on and off in normal use. I also have the correct factory nozzle. I can tell you that in a years time with 4 people using hot water the unit used 125 gallons of oil. As you know it provides virtually endless hot water. My unit is direct vented, which is the preferred method. I suggest that you install the correct nozzle and direct vent the unit. Calculate your actual oil usage and not some mythical number.

Dirk Wright

I agree

I agree that this unit is reliable and heats the water just great and doesn't use very much oil, but as with any combustion device, ideally you want the best combustion possible. There is no reasonable way for me to direct vent this unit, and I don't want to be exposed to the high CO levels that close the ground anyway. Has anyone put a combustion analyzer on one of these when it was direct vented? I ran a test with the correct oem nozzle and it was just as bad as the others. The problem is too much air and too much draft. My next task is to figure out a way to reduce the draft of this unit without interferring with the draft of the furnace, since they share the same flue for about 2 feet before exiting into the chimnney.

I admit that I have an urge to retrofit some other burner in there, this one is so frustrating to deal with.

mark smith

No ....

Bruce M.

Why are you not able to use a direct vent?

Is the unit in a basement? Because this is a unit that is designed and made in Japan you need to forget about your usual way of thinking. Japan does not have any oil and because it is imported, it is very expensive. This unit is designed to save lots of money and it will if you let it. Forget about the "numbers" as this unit does not usually run in a "steady state". My Toyotomi, for instance, does not run for more than 30 seconds when it has to bring the water up to operating temperature. I have mine set at 130 degrees. The water temperature at the outlet never changes even during very long showers. As a comparasion, think of the claimed gas mileage of automobiles, they are often a fantasy figure that has no bearing in the real world.

Dirk Wright

It's in the basement

Yeah, it's in the basement, and the first floor is not high enough above grade to run a direct vent, in addition to the fact that there is no really good place on the outside wall to put it. I have an available chimney so I decided to use it.

Any combustion appliance needs to be operating in a safe manner, and this unit was not. I think it's shameful that the manufacturer has not provided an adjustable air supply like every other oil burner on the planet. Every installation is different and therefore the combustion requires fine tuning to achieve optimum performance. I do not know how much CO this unit produces in a direct vent application since the manufacturer does not provide the information and I don't have one available to test. If it produces the same or similar CO in a direct vent application as it does in the chimney application, then I would be very afraid to direct vent it for fear of killing anyone within several feet of the outside vent. I would double the code requirement for distance to operable windows and doors just to be safer. A blank wall that large is sometimes hard to find. It's better to put the CO up in the sky than it is to put it at chest height.

mark smith

foolish question ...

from an old fool ...

are there approval ratings from say, UL on this ...???.

Dirk Wright

Yeah

It's UL listed. thanks.

Bruce M.

Which Model?

Do you have the OM-148? I sort of recall that it uses a 1.1 GPH nozzle. You can contact tech services here:

techservice@toyotomiusa.com

Dirk Wright

yeah

It's an OM-148 all right. I already talked with Toyotomi, thanks.

Actually the firing rate is about 1.05gph. The nozzle is rated at .85gph but is provided fuel @ 192psi.

It's a fancy burner in other respects, but the lack of an adjustable air supply is a really unfortunate omission. I think I'd rather use a cast iron hydronic boiler with a normal Beckett burner for domestic hot water instead, though I do not know how well that would work, or if it's legal, etc. I'm stuck with the Toyotomi until something really expensive on it breaks, which isn't likely anytime soon I understand.