Well N A, The Tankless Water Heater is the Bomb!

Hydroponic system?

Yeah 2.9 gallons is perfect actually. The "problem" with running high GPM pumps is that they will create high pressure and this eventual pump failure. I solved this problem by just creating a simple pressure relieve out of a hose t and flow valve. It was suggested to me that I keep the motor cool and so I bought a cooling fin sleeve that fits over the pump.

I haven't had any issues with it so far.

legallyflying said:

Hydroponic system?

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Hydronic, like boilers and shit

Lol. Oops. From what I understand, higher pressure pumps..pumps in excess of say 40-50 PSI are usually diaphragm type pumps. Impeller pumps are designed for higher flow operation. At any rate, for a summary about driving tankless heaters this is what I have leaned over the last two years about operating mine and trying various pumps...

1. Cheap harbor freight sump pump.. Worked for about a month. It's a high flow pump, and trying to push 50GPM through a heater that is rated for 4 GPM = really high back pressure..pump failure.

2. I thought the pump was maybe bad..got another one..lasted like a week.

3. If your barrels get any kind of debris in them it will clog the screen..flow reduction..heater may not turn on.

4. If your barrels are too small for your operation= inlet water will get hit, sometimes hot as fuck, which will toast the pressure bladder that triggers the heater to turn on.

5. The sure flow pumps are designed for high pressure and low flow. Despite this, the flow is still to high which means excessive pressure. You can hear the difference in how hard the pump is working.

6. Putting a T in the system helps eliminate this pressure.

7. Heat is a big enemy of brush life. The sure flow pumps are rated for continuous use if the optional cooling fins are added. I added the fins.

8. Marey water heaters are utter pieces of shit but if your nice they will send you replacement parts free. The ignition control on mine went south after a month.

9. And lastly, like most things, when the system is working its fuking awesome. Cranks out limitless co2 without virtually no operating cost. The downside is time spent tweaking with the system to get it right. Co2 can har huge effects on growth and yield. But much like nutrients, you have to modulate the amount of co2 based in time of grow.

Is it ultimately worth the hassle? Absolutely . Anyone who has carted canisters of co2 will tell you that they don't last tht long, are expensive, and are heavy.

legallyflying said:

If your so damned smart and have installed soo many taco pumps..which one will generate 40 psi of pressure?

Were are not here to debate the semantics of efficency of thermal exchange and the effects of temperature on liquid and vessel pressure.
That is all well and good, and I understand those concepts but honestly they don't mean fuck all here

The pump goes upstream of the tankless heater. Maybe HVAC guys have a particular lingo..but it can be placed on the "return side" which to use lowly people without Autocad (which I have by the way but I DLs a torent and crack for it as the licenses are stupid expensive) Most of us mere mortals see the return side as ...returning from the heater.

The tankless has a diaphragm that must be pushed enough to trigger the ignite switch. Placing the pump downstream of the unit would not make this happen.

Flow and pressure are too very different things. A particular flow does not dictate a given pressure (as the poster above found out)

Oh yeah.. Maybe I need an aquatat and an LPN cutin? Stop spewing shit for the sake of spewing shit and lend a hand on proper pump selection.

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I don't claim to be soo dam smart just many yrs in a trade , but my problem is that I forget I am talking to people with limited knowledge on the subject

AS far as pump PSI rating I assumed you would know to obtain a pump that is rated for at least the PSI you are looking if its over rated witch is a normal circumstance when retro fitting systems . it can be dealt with , by piping in a bypass system that would let you easy regulate the PSI needed to operate your appliance .............That is a no brainer in my feild,I apologize for trying to help , Good luck with your system.

Ok, all this talk about psi and shit had me thinking. Why would a tankless water heater require 30psi or greater to operate? Other than the pressure switch to start ignition. I got to looking at my hydrogen pro and it's psi requirements are 3.5-125 psi. To me if the units you are using require 30psi and you are having problems with pumps failing. I would look into replacing that pressure switch with a lower one. Flow is what is most important to proper operation of tankless water heaters not pressure.

Just some thoughts I had.

I highly doubt that unit would turn on with anything less than 10 psi. I don't know the exact psi it takes to turn my heater go, but I have experienced pumps with good flow, just not enough pressure

It says it right on the spec label on the generator. 3.5-125 psi. I don't see why it wouldn't. I can take a pic if you think I am making this up. They make many different pressure switches and again, I don't see how pressure is essential to proper operation of a tankless heater anyway. Proper flow is more important as the goal here is to remove as much heat as possible.

I'm not debating what it says. I believe mine says something similar. Problem is... What it says and how it actually works are two different things.

legallyflying said:

I'm not debating what it says. I believe mine says something similar. Problem is... What it says and how it actually works are two different things.

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could very well be I do not know for sure.

joe macclennan said:

most of em can carry well over 100 psi. This one should work fine.

http://www.grainger.com/Grainger/TACO-Circulator-Pump-4PC90?cm_sp=IO-_-IDP-_-RR_VTV70300505&cm_vc=IDPRRZ1

Oh and grundfos makes a great product too.
You'll need to purchase a flange kit also with any circulation pump.

Also, Putting an expansion tank in with a pressure cutoff switch would help extend the life of any pump. This will prevent it from deadheading which would overheat your pump causing it to fail. Especially if you are trying to push it to 30psi or more.Hope this helps.


To change to a diff. subject briefly.

Has anyone ever checked the exhaust co2 temp on your heaters. Just curious as to what temps your heaters are running. I'm gonna check tonite. I'm thinking it is not cooling as well as it should and I should flush.

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The maximum working pressure is 125 psi, but I don't think that means the pump can generate 125 psi. I think it means that's the maximum working pressure the casing and components can withstand. So if you install it in-line then the inlet pressure + the pressure the pump generates must be less than 125 psi.

The shut off head on this pump is 10 feet which is more than enough to get to my heater, but won't generate the required pressure. head = pressure * 2.31, or pressure = head/2.31 (for water). 10 feet of head = 4.3 psi.

The heater requires 40 psi to ignite (or so the manufacturer claims). 40 psi = 92.4 of head for water. I know the heater has ignited with pumps that can generate less than 92 feet of head, but not very well and not for very long. The last shurflo pump I had generated 100 feet of head.

I don't think that taco pump, or any taco pump from that series, will work on my heater. I need something that can generate 40+ psi with a low flowrate.

Could be.

You really can't beat a diaphragm pump for higher working pressure.

As I posted earlier if you are experiencing problems burning up pumps I would put an expansion tank and pressure switch inline with your pump.

Think of how well pumps operate. Same principle. Adding an expansion tank and pressure switch will assuredly extend the life of any
pump you decide to go with.

Another thing I was thinking is that I would look into getting a different pressure switch for your tankless water heater allowing it to come on at a lower pressure.

According to the mfg. specs my hydrogen pro can operate at pressures as low as 3.5 lbs

Yeah I don't understand why it has to be 40 psi. I guess maybe if you are specifically designing this heater to be used as intended for showers and such, then you probably do want 40-55 psi . I believe most city water is around 55 psi. But I don't really see it as necessary for the heater to function. I could get enough flow through the unit at a significantly lower pressure. Why did they choose 40? If you have a shitty pump that only delivers 30 psi and you are out in the dessert in your rv, then your hot water heater won't ignite? Or if your pump was delivering the bare minimum pressure to make it ignite, then your pump becomes slightly less efficient because of age and not it delivers just _under_ the minimum pressure it won't ignite? What's the rationale for the 40 psi trigger?

It was just a guestimate based on the listed pressure range of the pump and what I adjusted the pressure shut off switch to. Again, my system is working just fine.

legallyflying said:

It was just a guestimate based on the listed pressure range of the pump and what I adjusted the pressure shut off switch to. Again, my system is working just fine.

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What is a guestimate?

It's what your mom used for birth control

I know what the word means. I wanted you to clarify what "it" was that you were guestimating. This post makes no sense to me.

legallyflying said:

It was just a guestimate based on the listed pressure range of the pump and what I adjusted the pressure shut off switch to. Again, my system is working just fine.

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I was answering the question you posed on the previous post...what was the rationale ...

I asked why the manufacturer chose 40 psi as the minimum operating pressure on my unit. That is the manufacturer specification, but I don't understand why it has to be so high. It seems like it could safely operate at a much lower pressure.

I am no longer answering you because i hate the simpsons and think they are fucking gay. They jumped the shark like what.. 10 fucking years ago?

Cool thread im building mine this month, thanks for the info i almost gave those hydro immatation aholes my money. Gonna run drain to waste as i dont pay the water bill or have a water meter connected to my lot. Also dont feel like paying for electricity to run some massive pump, pay for a massive pump, or anything to do with a pump. Im down for saving the whales but the water will just be filterd and drip out of someone elces sink eventualy so i dont see the big deal there. Now if they were using natural renewable energy for electric maybe that would be a reason to run a pump? Just using natural gas in the first place isnt enviormentaly safe, they "frack" soil to get that stuff and farmers animals at the site end up growing extra toes and shit. Anyway thanks gain.