High Efficiency Boilers.

810f250

810f250

Griffs Services PowerWash
What makes a high efficiency boiler?

What is the efficiency of boilers of yesteryear compared to today?

Many may have seen me ask about the "black hole" of pressure washing machines, "the boiler", can we get better bang for our buck on fuel usage?

What's new in the industry?

Have you ever tested the efficiency of your current boiler?
 
Thanks for your response Paul.

"Dual Pass",...."Cold water wrap", design is not new, but how has this coil improved the efficiency of envirospec units?

Can you get us photos of the coils before they are wrapped?
 
I think the coil designs of yesteryear, were smaller and had less pipe and "pancakes".

As the non-industrial pressure wash industry demanded higher heat rise, more coil was added, but now times are changing again, we want the same heat rise with less fuel consumption, at least I do.

When do you step-up to 3/4" coil? What is the advantages? Do I dear ask the price difference.



Landa and Alkota have them. 300ft and 434ft respectively some big coils.

Landa claims to be super highly efficient.

Pressure Pro has a new insulating foam wrap on their new smaller skid units.

What else is in the works?

I like the idea that Kartcher has with preheat, I have seen the impact on boiler efficiency utilizing waste heat in the ammonia industry, and wondered why pressure washer manufacturers dont preheat the water entering the pump.

The pressure washer pumps are rated to 160F in most cases even if the inlet water supply to the coil was preheated to 125F before entering the coil, it should translate to some worth while savings. The technology is not new it is used in the carpet cleaning industry. I measured my exhaust on my 30 HP Kohler to be higher that the boiler stack temperature 700F and 420F respectively, lets use that waste heat.
 
You are right, there is a lot of heat thrown out through the coil. A BTU is the energy it takes to raise one pound of water 1 degree. That means that, theoretically, the 500,000 BTU coils that most of us use, could, if perfectly thermally efficient, raise the water temperature on a 5.5 GPM machine about 11,600 degrees.
What that tells me is that most of our coils are less than 1% thermally efficient, or in other words, we are losing a lot of heat.
If you look at the european style coils, you will see that their design is actually an upright design on many of the coils, that is shooting the heat down from the top, and then the exhaust is coming out the top. It makes for a more efficient machine, in my opinion. I had one for a while, and the reliability was not what I wanted, but it did burn much less diesel fuel.
 
Here is the formula Jim Gamble of Crystal Cleaning Company provided at the PWI Vegas Round Table and an engineer at Largo Cleaning Systems explained before this event.

Assuming 75% Boiler efficiency. Which is about best efficiency.

(Pump GPM output X 60 X 8.33 X Desired Heat Rise)/ .75 /140000 = GPH Firing Rate.

the other limiting factor would be the coil internal diameter size. You could only fit so much fire in so much of a space.

For a 20" diameter coil, Beckett recommends 4.00 GPH, I run 3.25B nozzle at 140psi in my 20" dia. 1/2" coil at a little over the 4.00 GPH recommended limit, and the water gets to what the formula says it should be for 8.5 gpm pump.

In the winter my "Hot Water" will be "Luke Warm" unless I preheat the inlet to the boiler, or "Daisy Chain" boilers somehow.

Here are some common pump gpms plugged in the formula

Diesel Firing Rate (GPH)

Desired Heat Rise 130F 140F 150F
PW Pump
4.0 gpm = ______2.47 2.66 2.85

5.5 gpm = ______3.39 3.65 3.91

8.0 gpm = ______4.93 5.31 5.69
 
I agree Nigel, there is a lot of wasted heat that could be used, the carpet cleaning companies utilize that extra heat and they put out like 3gpm at 250 to 300 degree heat, at least that is what they claim to be coming out.

Carpet cleaning does not need the "impact" like what we need for cleaning concrete where at the higher temperatures, as soon as the water leaves the coil, it starts losing heat, as it travels through the hose it is losing heat and finally when it comes out the end of the nozzle, if it is still hot enough, it is flashing to steam so you are not getting the hard impact like what you would get if the water was at a cooler temperature.

I think that one issue could be liability for the hoses and rubber parts. Most of the hoses I have seen are only rated up to about 275 degrees but I think that with that temperature running through them all the time along with downstreaming chemicals, it will finally take it's toll and you could start to have hose ruptures and people getting 2nd and 3rd degree steam or water burns.

I think that the hose manufacturer's know that not too many machines out there make that kind of heat consistently and they probably do not test their hoses to failure with hours and hours or days and days of testing at those higher temperatures to see how many hours it takes at what temperatures to see when is the breaking point. Since not that many machines out there can realistically make that consistent heat for a long period of time they are probably not worried about it.

Even Jim says that on some jobs at the higher temperatures he has to change out hoses about every 2 hours because they start to break down, you will start to see the black water and then pieces of hose start to come out or start to clog the nozzles.

I think that the technology is out there and probably could be used but you would need the guns to be open dump guns for a safety issue along with a person at the machine to kill the burner if something happens because you would not want to just block the valve at the end of the hose with that kind of heated water with hoses only rated up to 275 degrees, mostly 250 for a lot of the hose brands out there.

Even Jim and I have talked about pre-heating the water so when you do get your heat rise, you will be easily over 225 or 250 degrees but then you would need to do a lot of plumbing or use another burner but with a thermostat set so you don't cook your packings, maybe a temperature set point of no more than 125 or 140 degrees initially. Then you need to find a hose that is rated good enough or higher to handle not only that hotter water but under that same pressure and then the PPE for the workers to keep them safe so if something did burst, they would not get burns.
 
810f250 said:
Here is the formula Jim Gamble of Crystal Cleaning Company provided at the PWI Vegas Round Table and an engineer at Largo Cleaning Systems explained before this event.

Assuming 75% Boiler efficiency. Which is about best efficiency.

(Pump GPM output X 60 X 8.33 X Desired Heat Rise)/ .75 /140000 = GPH Firing Rate.

the other limiting factor would be the coil internal diameter size. You could only fit so much fire in so much of a space.

For a 20" diameter coil, Beckett recommends 4.00 GPH, I run 3.25B nozzle at 140psi in my 20" dia. 1/2" coil at a little over the 4.00 GPH recommended limit, and the water gets to what the formula says it should be for 8.5 gpm pump.

In the winter my "Hot Water" will be "Luke Warm" unless I preheat the inlet to the boiler, or "Daisy Chain" boilers somehow.

Here are some common pump gpms plugged in the formula

Diesel Firing Rate (GPH)

Desired Heat Rise 130F 140F 150F
PW Pump
4.0 gpm = ______2.47 2.66 2.85

5.5 gpm = ______3.39 3.65 3.91

8.0 gpm = ______4.93 5.31 5.69
Click to expand...


Maybe you could plumb your exhaust from the engine into a box with a small coild inside it that leads to the pump so you get a small heat rise there or maybe add another coil to the exhaust of the boiler for more heat rise then to the pump.

That might not be a lot of heat rise but in the winter time it might make a lot of difference on cleaning gum.
 
Great points Chris, but I am not trying to hit no more than 250F at the coil exit, I dont think I need to, more interested in burning far less fuel, that could as be a "green" feather in a companies cap.
 
Christopher said:
Maybe you could plumb your exhaust from the engine into a box with a small coild inside it that leads to the pump so you get a small heat rise there or maybe add another coil to the exhaust of the boiler for more heat rise then to the pump.

That might not be a lot of heat rise but in the winter time it might make a lot of difference on cleaning gum.
Click to expand...

Thats what I was thinking, use a carpet cleaner heat exchanger in conjunction with the diesel boiler!!
 
I think it would be a great idea if they could be mass produced so all we would have to do is attach them, plumb them and run a hose to the pump from the heat exchanger for more of a heat rise, that might even save some fuel to add more to the "green" of being more environmentally nice.

Now........Who out there can start building them for us??????
 
3/4 inch coil has both advantage an disadvantages the water has more flow but not as much coil to flow through=water is not staying in the coil as long to get heated up.The 1/2 inch coil has less flow but the coil can be longer and the water stays in longer giving it more time to heat up.I thing the 3/4 coil would be a lot less effecient.The burner would have to cycle more and use more fuel.Blaine is setting up those big wash trucks to heat the water through heat exchangers and the truck engine as well.
 
You exhaust your machine thru a 2 inch stainless pipe maybe 3 or 4 ft long and you take your supply line to your tank and use tubing for the last few ft and you tightly wrap the pipe with the tubing to capture the heat.in essence you are creating a preheater which all industrial boilers use.If you can gain 10 to 20 degrees you will be alot more efficient.

you could also make a stainless box that the machines exhaust blows onto and the supply water has to pass thru the box to fill the tank.It would be a simple plate exchanger.The box should have baffles in it to create retention time to increase the heat gain.I say use stainless as it would build less scale inside over time.

The machine is creating heat And we are losing it.The fastest way to make a boiler more efficient is to preheat the water going in.
 
I have thought about adding another coil (have an old one that I haven't used in a few years) and mount it parallel to the other coil, then take the end off the first coil and fab a bend to connect the 2 coil wraps together and also connect the 2 coils together. The exhaust for the first coil wouldn't be able to get out till the end of the second coil. These would be horitzontal coils.

Have also thought about laying down a vertical coil that I have and add the other coil to it (would look like one LONG coil)

More or less the original coils exhaust would heat the second coil some. I would put the thermostat at the end of the second coil.
 
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