Another Power Washer question

[RipTide]

I have a 3.5GPM/4000PSI pressure washer, but at my new house the water flow is pretty slow, maybe around 2 to 2.5 GPM. My manual says that if the water flow is not sufficient than it could damage the pump mechanism. Can I safely run this washer and just turn down the PSI so that it would handle the lower water flow?

[twstanley]

Is the well refill rate that low or is what comes out of the tap that low?

If your well refill rate is that low I would guess you could run your power washer quite a while on the water in the pressure tank ( if you have one ) and in the well casing already.

Do you have a pressure tank? How big? A well? How deep, how big is the casing, how far down is the water, how far down is the pump? If you provide that, somebody can tell you how much water you have on hand in the casing above the pump that you can use before the well recover rate becomes the deciding factor.

[GaryM]

I think he's saying that the flow from the faucet is that low. Perhaps that point can be clarified?

If power washers are like air compressors, and that may or may not be the case, at a lower pressure the flow might actually be higher. I'm certain someone will be along soon with the facts.

The issue with trying to pull water into the pump is, I think, cavitation. The inlet side of the pump would be low pressure, but I'm not certain how the damage, other than possible pump overheating, would occur.

[RipTide]

A little clarification. The water is coming from my tap. The guy that built the house apparently used the smallest pvc line he could use from the main to the house. I guess he thought he was saving money. I will at some point have to redo all of that just to get adequate pressure for showering, etc. I did a quick test by filling a gallon bucket and timing it and it looks like my flow rate is about 2 to 2.5 gallons per minute which is below the specs on my pressure washer. I have been considering getting another line run from the main at the street with the biggest pipe I can get and using it for the pressure washer and down the road tying it in with the house.

[twstanley]

Hmm, I see now. How about filling a 50 gallon barrel with water and hooking your pressure washer to it when you want to do some pressure washing?

Are there any other choke points of the water coming in? An old whole house filter that needs changing? I would think that even 1/2 inch pvc would flow more water than that to one fixture, I guess if its a long distance or going uphill that could cut the flow rate. I certainly am no expert on that, I am sure someone else will comment on that ( hopefully ).

[Pat]

Hey, Rip, I'm some surprised to hear the tap has such a low flow with plastic plumbing of recent vintage. There has to be something not in evidence to cause that low flow.

Do you have near neighbors with significantly better pressure and flow rates? You might want to invest a few bucks ($5-$10) in a water pressure gauge that screws onto a hose connection. You'll want to get a pressure reading with no water flow and again with various numbers of faucets turned on. The spread in pressures will give an indication of how much resistance to flow you have in your pipes. You may have low pressure being supplied as water comes from your meter. Is the valve turned fully on at the meter?

As for damage to the pump in the washer. The pump is cooled and lubricated by water. Loss of sufficient water will cause problems. Additionally, cavitation from sucking a vacuum on the intake can cause serious errosion of metal parts.

One consideration, if you can stand to have to "duty cycle" your spraying would be to put a surge tank (like a pressure tank with diaphram as used for a well) between the water spigot and the pressure washer with a check vaslve on its input side. The tank will fill up to the highest capacity it can considering your pressure and will then help supply water to your washer... for a little while. You then have to stop spraying for a moment to allow the thing to recharge back up in pressure. This assumes yo have adequate pressure in a "static" situation and only lose pressure when there is flow.

If you are familiar with electronics, think of it as charging a capacitor through a high resistance and then discharging it through a low resistance. Another way to visualize it is that it works like a conventional flush toilet. The tank fills slowly through a small tube and is subsequently flushed at a high rate of flow, for a little while. Then yo have to wait for it to fill before you can get another blast of water.

Another solution is to buy an automatic booster pump to put between the water source and the consumer. this can be between the meter and your house or between a hose bib and the washer. This will cost you $300 and up. Harbor Freight has a good one for $300. I don't think it is a Chinese import.

Most important first consideratiion is to get a pressure gauge and find out if you have low pressure all the time or just when there is flow. Also be sure to check the valve at the meter to ensure it is WIDE OPEN.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[RipTide]

Thanks Pat, I will get a pressure guage and get more info. I do believe that the pipe from the main meter is only 1/2 inch and I had always thought that was the problem. I did have one plumber look at it and he gave me a huge estimate to replace the pipe to the house, which is approx 100 to 150 yards from the main. I assumed he had checked to see if the main was turned on to the max, but I think I need to recheck that as well. I will post what i find out.

[BlueRidge]

If you've got a 1/2" pipe running 100-150 yards, that's your problem. I don't think that would not meet code in most areas. I'd check into that - if it doesn't meet code, you might be able to force the original plumber to bring it up to code on his dime. (Meaning, rip it out and put in what he should have put in the first time around.)

You should have a 1" line MINIMUM for that distance. 1 1/4" would be more reasonable, and I don't think 1 1/2" would be overkill.

[RipTide]

I took some of the collective advice and put a pressure guage on my front faucet and got 60 PSI. I then went around to the back of the house which is one level down and tested the spigot there and got 80 PSI. I don't know how this works unless the second spigot being lower helps with the pressure. So I did another flow test using a new 5/8 inch hose and much to my amazement I got 5 GPM. I do think I probably screwed up my initial estimates due to the fact that I tested my initial flow with a single gallon jug and I had a hose attachment on the end of the hose which may have restricted flow some. I will go ahead and admit to being a knucklehead right now, but if I had not had the advice of you guys to do it right, I would not have found out that everything is okay. So thanks again.

ps I am still going to talk to a plumber about running a bigger size pipe from the main to the house.

[GaryM]

Any attachment on the end of the hose will reduce the flow, if it's opening is smaller than the hose it's attached to. The hose bib you have the hose attached to reduces the flow, but it's difficult to overcome that problem. [img]/forums/images/icons/grin.gif[/img]

Glad it seems that you'll be able to use your power washer afterall.