# tankless water heater works, new problem now



## Sparticle (Nov 1, 2004)

Thanks to everyone for advice on the tankless water heater. Turns out, the unit was defective. They sent another and it fired right up. Now, I'm questioning my plumbing system. We're off the electrical grid here and went with a Shurflo pump and pressure tank. The pressure can't support more than one faucet open at a time. I've got 1" PEX as the main branch going down to 1/2" PEX. I'm thinking the 1" is too big for the Shurflo. The pressure tank is set at 43. What say you?


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## jwal10 (Jun 5, 2010)

Doesn't matter what size the pipe is, it is to much flow for the pump at the faucet. Actually the bigger the pipe is, the less resistance, the better. You are using too much flow. Device uses water, pump kicks on but can't keep up and pressure drops. What volume is the pump rated at, gallons/hour? Need a flow restrictor, at faucet or inline to regulate flow. If inline then no pressure at faucet, just drops out....James


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## jwal10 (Jun 5, 2010)

How big is pressure tank? It needs to be big enough to supply enough water for a single use, then the pump refills tank to pressure for next use. Sounds like you need very low flow restrictors in each device (faucet, showerhead, washing machine fill, etc)....James


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## Sparticle (Nov 1, 2004)

I got the biggest pressure tank Lowe's had. The pump is 2.8 gpm. I wonder if that is enough.


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## Sparticle (Nov 1, 2004)

The pressure tank is the 36 gallon size.


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## chrisl (Jan 20, 2006)

You really need a bigger pump, 2.8 gpm is very low, you need to figure out what your head pressure is (IE static pressure or resistance) then you need to size your pump according to your gpm requirements. I'm sure the water heater has a minimum gpm value, plus all your faucet have a gpm rating. Do you have a washing machine? Do you have a water softener?

Try the following link, i use it all the time to spec out well pumps this might help. Don't let anyone tell you they know what you need unless they know how much pipe you have of each size and what the gpm requirements are for each appliance and faucet. 
*At this stage of the venture the pressure tank is not important, you need to know how much gpm (flow) you need first. After you have determined this and selected the right pump for your situation, then you can size your pressure tank for the pressure and pump cycle you want*.
Hope this helps.
Chris

http://www.buypumpswholesale.com/page/worksheets/calculators


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## Sparticle (Nov 1, 2004)

This has become too much for my feeble little mind to comprehend. I called a plumber. He says that a Shurflo 5.7 gpm pump will do the trick. He also recommends 1/2 pipe ran throughout the house. This is okay with me since I ripped out all the PEX the other day, but is 1/2 throughout sufficient? He claims the 36 gallon pressure tank is okay as well. How 'bout it?


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## Sparticle (Nov 1, 2004)

Oh, its a small house. One kitchen, one bath, washer dryer, outside faucet. Thanks everyone.


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## Bearfootfarm (Jul 13, 2006)

1/2 inch is standard *inside *most houses, although it really doesn't matter that much in relation to your problem.

Once the system is full, the pump determines the pressure and the faucets determine the outflow rate


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## jwal10 (Jun 5, 2010)

Are you talking about having enough hot water? Tank is big enough. Pipe size does not matter. Flow of device controls gpm.
Put flow restrictors or heads on the system, lower the pressure. I run 20 lbs and restrictors to cut water use. Faucets can be cut to less than 1/2 a gallon. Showerhead to less than 1. Takes longer to fill my little washing machine but no bother....James


http://www.conservationwarehouse.com/


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## chrisl (Jan 20, 2006)

You will be fine with 1/2", there is quite a bit of new construction that is using 3/8" PEX running to each faucet, of course this is off of a manifold, not a branch and tee setup. If you could afford it I would recommend a Manabloc manifold with 3/8" Pex outlets. The Manabloc will help you keep a balanced system, that is if someone flush the toilet the kitchen sink won't quit running water, or if the washing machine is filling, you could still get water at bathroom sink.


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## Sparticle (Nov 1, 2004)

This pump that is 5.7 gpm has a psi of 65, Seems high and I don't think its adjustable. Is 65 too high?


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## Bearfootfarm (Jul 13, 2006)

> This pump that is 5.7 gpm has a *psi of 65*, Seems high and I don't think its adjustable. Is 65 too high?


The pressure is normally controlled by a "hi-low" switch that can be adjusted, usually over a 20-30 lb range.

It is where the wiring attaches to the pump, and will have a tube running to the water line so it can read the pressure

They usually look something like this:










http://inspectapedia.com/water/WaterPumpAdjust.htm

You'll also need to check the air pressure in your tank. It has to be done with the water off and the tank drained. There willl be a "tire valve" at the top of the tank, and the pressure needs to be 2 lbs less than the low setting on the pressure switch that turns the pump on.


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## Sparticle (Nov 1, 2004)

This is a Shurflo pump. DC power. The smaller pump I have has a screw to adjust the cutoff pressure but this bigger pump does not. How do I deal with 65 psi? It's a Smart Sensor pump. Thanks to everyone.


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## tom j (Apr 3, 2009)

I have 65 psi ,, thats what I have run for over 35 years ,, my son just put in a new well and that is set at 65 psi .. all the pumps that I have seen are set at around 65 + or - a pound or two .. any less and you have slow floe water ,, hard to shower in ..


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## Bearfootfarm (Jul 13, 2006)

This should work:



> 3/4" Bronze Water Pressure Reducing Valve
> 
> Excellent choice for both residential and commercial applications
> Adjustable pressure range 25-75 psi


http://www.lowes.com/pd_21501-18701...br|0||p_product_qty_sales_dollar|1&facetInfo=


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## Sparticle (Nov 1, 2004)

Why do I need a pressure reducing valve? THe pump cuts off at 65 psi. Will this reducer change that? I'm sorry but I just don't understand these things.


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## Bearfootfarm (Jul 13, 2006)

Maybe I misunderstood
I thought you meant you wanted to lower the pressure coming *into the house*.


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## Sparticle (Nov 1, 2004)

I only want to lower the pressure if I need to. Do I need to? Is 65 psi okay for my tankless water heater? It works great around 40 psi. I guess I always thought that 45 psi was the norm. 65 is a lot higher than that. I know nothing about this. Thanks for all the help.


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## Bearfootfarm (Jul 13, 2006)

65 isn't abnormally high.

Many switches are set from 40-60

If you think less pressure would help the water heater, you could plumb in a pressure reducer valve in just that one line


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## Sparticle (Nov 1, 2004)

Okay, I understand that. Good. At what pressure should I set the pressure tank?


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## Sparticle (Nov 1, 2004)

It appears that the pressure is adjustable on the pump. I have lowered it and feel much better about it. Thanks to all for your generous advice.


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## Bearfootfarm (Jul 13, 2006)

> At what pressure should I set the pressure tank?


The air in the tank should be 2 lbs less than the pressure at which the pump turns on.


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## greg273 (Aug 5, 2003)

Sparticle said:


> I got the biggest pressure tank Lowe's had. The pump is 2.8 gpm. I wonder if that is enough.


 You got the Shurflo 2088? We used that for our domestic water for about 5 years, and it was pretty weak, the pressure switch on that thing is not very good either... upgraded to a bigger AC pump and are enjoying much better pressure as well as less run-time.


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## texican (Oct 4, 2003)

When I was off grid, I had the same basic setup.... 12vdc shurflo, pressure tank, and hot water heater.... Had pressure for only a few minutes, and then the flow was a trickle... (what the pump could put out, just a few gallons per minute). This was 'pre-internet', so didn't have any one to run the problem 'by'... Finally took the pump and pressure tank out, installed 1" cpvc for the hot water, and used gravity flow... ended up with more water flow (only about 12 or so lbs of pressure, on a good day) without the pump or pressure tank.

Know it's frustrating, finding the narrow sweet spot where a homebrew system works, but it is nice once you find it!

Any chance of building an elevated water tank in the future? If your pumping water out of the ground, you just plumb it to the height of the tank. Even the shurflo will push it up to a high storage tank (pressure of the pump = 2x feet of height)


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