DIY Instant hot water heater

I may be nuts about this....but please give me your thoughts.

I've been thinking about setting up an instant hot water heater to shave some time off the brewing process....thing is that they are expensive as hell....so I was thinking that it might be possible to use a copper coil (like a chiller, just wound up a bit tighter) and place it on my extra bayou jet burner stand.

The water goes through it, comes out hot and then into HLT and MT for strike water. Speed of water flow would determine the temperature at output.

I was even thinking of using an old corny keg and cutting the top and bottom off to use as a type of flu and to place the coil inside. Might even create a small chimney at the top to trap some additional heat.

Has anyone ever done this? Any concerns? Do you think that the temperature would actually rise enough?

Thanks in advance

I believe you would have two problems
1. the water would have to travel really slowly through the coil to pick up significant heat - assuming its ground temp to begin with
or
2. why not just heat the water and dump it in, it would have to be boiling to get the highest rate of energy transfer and that just seems redundant.

look into steam injectors

I like the way you think though

It has been done. I forget what it was called.

I think the biggest issue was the steam pressure created within the piping system.

You're thinking of a flash boiler.

Your concept is correct in using a coil and varying output for temperature. There have been a few threads.

Funkatollah said:

You're thinking of a flash boiler.

Your concept is correct in using a coil and varying output for temperature. There have been a few threads.

Click to expand...

That is it.

Pretty obvious to me: If your burner puts out say 35,000 BTU's, that's all you're gonna get out of it no matter whether you're heating a HLT or copper tubing.

M_C

Misplaced_Canuck said:

Pretty obvious to me: If your burner puts out say 35,000 BTU's, that's all you're gonna get out of it no matter whether you're heating a HLT or copper tubing.

M_C

Click to expand...

I thought about that....I'm just wondering if it's not more efficient to heat a copper coil then trying to heat a keggle.

In the end adding a burner would be like using 2 times 35,000 btu....no?

In other words, first heat with coil, then with burner under HLT.

pilzner said:

I thought about that....I'm just wondering if it's not more efficient to heat a copper coil then trying to heat a keggle.

In the end adding a burner would be like using 2 times 35,000 btu....no?

In other words, first heat with coil, then with burner under HLT.

Click to expand...

Sounds good to me, hell if you have a extra burner go for it. You would think if you set the coil up like a rib cage entering from the top and coiling down and then back up would be the best way to do it?

If I had a extra burner I would do it. I like to build things and if it would shave some time of the brew day then I would call it a win!

This is more or less what I'm talking about....but I think this is for steam.

Nothing to do with this thread, but is your signature suppose to say "Look Like a Pro" or is that part of the joke that I am not getting?

This was the prototype water heating flash boiler on the manual brewing system https://picasaweb.google.com/kevin.ladue/InstantWaterHeater#5018859429657128834. It functions as water heater and steam boiler for steam injection RIMS heating.
This is the larger boiler for the automated system https://picasaweb.google.com/kevin.ladue/NewBoilerAndMixer#5244098708413101458. This unit will heat 4 degree water to 165 degrees at .5 gpm, and generate enough steam to heat water from 130 to 212 degrees at 1 gpm flow. This is the automated brewing system it provides strike water heating, sparge water heating, and superheated steam for step mashing. The other pressure cooker steam systems are not able to generate or maintain continuous steam flow like this system will, and electric RIMS system can not develop the amount of heat released by the steam injection.

Misplaced_Canuck said:

Pretty obvious to me: If your burner puts out say 35,000 BTU's, that's all you're gonna get out of it no matter whether you're heating a HLT or copper tubing.

M_C

Click to expand...

However, the difference in surface area is significant. A 14" pot will have ~154 sq in of surface area over which to absorb heat. 3/8" copper line will have that much surface in 10.8 feet. A 25 foot, 3/8" line will have 353 sq inches of surface area. That's a 1:2.3 ratio.

Someone double check my math for me, though.

The automated SS tubing boiler has 754 square inches surface, and this copper tube boiler has 942 square inches of surface area https://picasaweb.google.com/kevin.ladue/Boiler02#5463697378793300258. 1/4" tubing is easier to bend and work with than 3/8" tubing, but flow has to be from bottom up to avoid air bubble blockage of tubing during heating.

vince805 said:

Nothing to do with this thread, but is your signature suppose to say "Look Like a Pro" or is that part of the joke that I am not getting?

Click to expand...

Ha, don't know what happened....but yea....look like a pro.....guess I should proof read like one too

kladue said:

The automated SS tubing boiler has 754 square inches surface, and this copper tube boiler has 942 square inches of surface area https://picasaweb.google.com/kevin.ladue/Boiler02#5463697378793300258. 1/4" tubing is easier to bend and work with than 3/8" tubing, but flow has to be from bottom up to avoid air bubble blockage of tubing during heating.

Click to expand...

Kevin, Thanks so much for jumping into this. sort of off topic, but how does the steam work for the MT steps? Is is a jacketed MT?

Also in regards to the flow of liquid....your system goes straight to the bottom the spirals to the top? Where did you get the fitting that you use on the top (5 way compression fitting?)

I was the originator of those steam systems.

I bought an inline hot water heater today to replace my HLT.

Amazon.com: Eccotemp FVI-12-NG High Capacity Gas Tankless Water Heater: Home Improvement

I paid $230 for mine. Sounds expensive, but it takes a kettle, burner, gas control valve, thermocouple and controller to do what it will do.

And I can use it for other things, like supplying wash water.

The thermostat only goes to 140, but I'll modify it. I'll use it for mash in and for sparging.

I'm tired of waiting for water to heat up in the HLT.

I'll have a burner under my MLT, so if my mash in water is a bit cold, I'll just heat it up.

I am not sure about the who was first with steam, but the manual steam injection system was built in 2003, and the automated system in 2008, and appear to be the first ones using steam injection to circulating wort for step mashing. The steam injection into the mash method has been around since the mid 90's, but was mostly abandoned because of the noise and difficulty hitting desired step temperatures. A few folks are still trying that method but pressure cookers are limited in steam generating capacity and temperature control is hit and miss.
The SS tubing boilers provide hot water at high flow rates, and superheated steam at low flow rates, all of which flows through steam/wort mixer into MLT. The systems were built so no plumbing changes are made during brewing, just water flow and propane flow to burner adjustments to maintain temperatures. The steam injection raises the wort temperature by the heat release from condensing steam in the flowing wort, not from difference in temperature of steam and wort like the electric RIMS system, and is quiet as the steam bubble size is controlled by diffuser screen opening size. Heat source is adjusted to control mixer temperature as system is running, and step mashing maintains desired wort temperature leaving mixer chamber. Step time is related to liquid exchange and mash heat absorption times, heat source is reduced as mash temp rises during step for steps of 25 degrees in about 10-12 minutes.

kladue said:

I am not sure about the who was first with steam, but the manual steam injection system was built in 2003, and the automated system in 2008, and appear to be the first ones using steam injection to circulating wort for step mashing.

Click to expand...

You beat me then. I converted a corny into an electric steam boiler and mashed with it in 2006-2007.

I have abandoned steam mashing by direct injection (for now anyway) because the steam bubbles disturb the grain bed until they cool down enough to burst.

If I was going to steam mash again, I would install a SS plate in the mash and inject the steam into it or underneath it so that the bubble collapsed before it was in the main part of the bed, thus not disturbing it as much.

Steam mashing has merit, but as you see, it takes a bit to get it working exactly the way you want it to.

I am going to try direct heating my next mash tun. Should I not like that, I'll be returning to steam mashing.

I worked with the pressure cooker and steam into mash setups in the 90's, always the same problem, collapsing steam bubbles caused problems and lot's of noise. Then I installed a starch cooking system in a paper mill that injected steam into the flowing starch solution and realized that was the approach needed for step mashing, quiet and precision temperature control. After scaling the mixer down to 1/2" swagelok tee's and a 1/4" diffuser screen, the manual system was built. A bit of tweaking and I had a system that SWMBO and I could operate to brew competition beers on. The next generation system doubled the boiler tubing from 40' to 80' of 1/4" stainless, and strike water flow was raised to .5 -.7 GPM based on water inlet temps. Nice part about this approach is the boiler feeds out through mixer and plumbing is hard piped to MLT. No exit valving on boiler prevents pressure buildup, and all flow is into dispersion ring inside MLT which lets you fill,recirculate, and sparge without changing plumbing. That is why the automated system plumbing connections are on the backside, no hose switching needed, and a shop vac handles solids during cleanup.

The reason they are as expensive as hell is it's hard as hell to instantly heat water.

Setting up a recirculating deal like one of those HERMS or whatever is one thing, but heating up water more than a few degrees in one pass is extremely difficult due to the heat capacity of water. Most instant hot water heaters are gas, and the electric ones draw hundreds of amps.

I wouldn't even try to make one yourself. There's no way it would be worth it.

Instant and worth it are relative. The one application where it makes a lot of sense is in producing hot sparge water for fly sparging. If you're pulling off a 45 minute fly sparge, you don't need 9 gallons at 170F at the first minute. You need .20 gallons the first minute. The increased surface area is also a much more efficient use of fuel. A typical burner under a stainless pot only puts about 40% of the energy into the liquid.

Instant water heating is not rocket science, a few of us here have built successful systems with flash boiler designs. Even with electric heating elements you can do sparge water heating at .2 -.25 Gpm with a 4500 watt element. Most of the cost associated with the on demand water heaters is the manufacturers liability insurance cost, not the materials, just like the "Cadet" brand recessed electric heaters are today.
The old system uses a 6" ring burner and it can raise water to strike temp easily at .3 Gpm, the newer boiler raises .5-.7 Gpm with a 4" high pressure burner with an measured btu yield around 36K (flow, inlet temp, and outlet temp are measured). I was able to hit 1 Gpm with copper boiler but could not maintain superheat in steam mode as boiler exit gas temp was too low, so I switched back to SS boiler.

Why would you need to heat hot water if it's already hot?

Just poking fun at calling it a "hot water heater" as opposed to a "water heater".

I need to study what you've done with steam heat in more detail.

I've designed my upcoming system build to use a direct fired MLT. It
bothers me to do so, but I'll see how it works.

I'd love to do something with steam, but like you too, realized the
collapsing steam bubble is an issue. I've thought of other heat exchange methods between the steam and the mash, but all have issues of one sort or another.

BTW, why don't you use a domestic hot water heater as your steam
generator ? At the temps we are talking about, ie 240F and down, they
will easily withstand the temperature and pressure.

The up flow boiler design allows for superheating, boiler materials were free, rolling the 1/4" coils around 2" pipe was easy,and the inlet/ outlet fittings are 2 swagelok fittings welded together (SS-400-4 + SS 600-P). The copper boiler experiment was 6 - 16' coils silver soldered to swagelok brass cap fittings (B-1010-C) for 1/2" copper pipe, does great for water, not enough burner output for steam.
You could copy the tankless heaters by using a finned coil oil cooler and some sheet metal, burners could be fabricated to work with rectangular coil or a round burner with sheet metal shroud built to transition from round to rectangle shape of coil. With flow meter on water inlet and thermometer on the water outlet you could control it manually like the old manual rig I have.
Direct fired rims is a good approach, just need to watch leaving wort temperature and turn down burner output as mash warms like the steam system. It has an advantage in simplicity and ability to add more heat for larger steps than HERMS might be able to, and definitely more than the electric RIMS can safely.
Here is an older schematic of the automated system https://picasaweb.google.com/kevin.ladue/BrewingSystemSchematic#5217718771936179554, the water measuring tank and pump were eliminated in the current system.