PDA

View Full Version : Ejection system severe water hammer. How can I combat this?


keithl
Jan 10, 2011, 07:57 PM
I have an ejection system located at the bottom of my 3 story house. It climbs approx 27 feet to the street via all sorts of 90 degree turns. I have 2 lines and alternating 1/2HP pumps. One line has a2 check valves the other nothing. Both more times than not emit severe water hammer. How can I combat this?

massplumber2008
Jan 10, 2011, 08:24 PM
Hi Keith:

In most cases, each ejector pump discharge pipe should have its own check valve, but without knowing how the "alternate pumps" are set up and when they fire off, etc... I can't say too much on that.

To reduce the check valve hammer you could try locating the check valve(s) higher up say, a couple feet before the pipe first goes horizontal, and see if that improves things. It should.

I usually install the compression check valve... see image (white) and have never had any problems with them, although I can't remember trying to lift the sewage 30 feet, either!

Pasco also sells a check valve called the SILENCER... see image (red). I have never used one, but they say it is great at reducing the hammering/clunk associated with these pumps.

There should be a 5/32" (I think) hole drilled in each discharge pipe just above the pump and still under the cover... prevents air lock.

You can check out more info. On sewage ejector installations at Zoeller Corporation (http://www.zoeller.com)

They have installation instructions if you find the pump.. look up the zoeller M267 model... then click on the install PDF. File.

Questions? Let me know... OK?

Mark

keithl
Jan 10, 2011, 08:51 PM
Thanks enormously. I heard about spring loaded check valves but never the silencer. And thanks for the website reference. The check valves I have are only about 9ft above the pumps so I have to get them higher. Also if you can advise - the pipes are strapped to the inside walls in the lower floor and when the pump comes on it shake, rattles and rolls the wall it's attached to. I can instead hang them from the joist about 6" above and really strap them to it. Will that get rid of the shaking without compromising the stability of the pipe?

I'll check for the hole in the pipes in the spring. I'm in Lake Tahoe and we are under lots of snow already.

Thanks again - this has been plaguing me for a couple of years.

massplumber2008
Jan 11, 2011, 05:53 AM
If you strap the pipes that tight there is a good chance the pipes won't be able to expand/contract properly and one of the pipe fittings could break, so hold off on strapping them in just yet.

Also, having the check valves up 9feet already is plenty high enough... I'm wondering if you shouldn't put the check valve(s) on the HORIZONTAL instead... maybe. Here, the check valve(s) would need to be oriented exactly right for the flapper to close properly, but with the head pressure you have above it may be helpful... hard to say.

At this point, I would call the zoeller pump company and speak to the technical department about this... even if you don't have zoeller pumps (although I wouldn't exactly tell them that). You have a pretty special situation with that 27 feet to lift the sewage.

You can contact them at the link I provided above. I would be very interested to hear what they think the best approach would be... ;)

Also, that I know of, spring loaded check valves are not appropriate here as there are too many "working parts" inside and they tend to gunk up and break down quickly. With that being said, I was trained to use the compression type check valves as posted above and have never had any complaints of noise like I hear on this website (and others), so I would look into these and the silencer.

Call the technical department as mentioned... hate to see you do work on these only to find things got worse... ya know?

Mark

keithl
Jan 11, 2011, 09:13 AM
The check valves are on the horizontal not the vertical so that's fortunately not making it worse. Sorry by strapping i just meant to restrict horizontal sway but expansion would be possible.
Already located the distributor in town that has the 'silencer' and will contact today.

i'm excited just to have hope this will cure this and thanks once again.

Now all i need is an answer to my baseboard heating question!

massplumber2008
Jan 11, 2011, 09:16 AM
Post it at the heating forum here at the AMHD to get the most opinions, and you can also post it here. I have some pretty extensive experience with baseboard...

PS: Lose the caps... gets people all excited around here as it is considered a form of yelling online... I guess? Thanks!

keithl
Jan 11, 2011, 09:29 AM
Sorry, I was halfway through before I saw the caps were on.
Baseboard. 4 yr old system with 5 zones, air scrubber and Munchkin boiler. Last 2 years have developed so much noise from the baseboards when they come on, it seems something has changed. The copper pipes through the floor are not hindered but they clang slowly then increase and then there's lots of pinging from the individual fins. The installer just says that' rapid expansion caused by going from cold to very hot in minutes. So why didn't it do this in the first 2 years?

massplumber2008
Jan 11, 2011, 09:50 AM
I don't want to discount what the installer has said as they USUALLY know best, but air scrubber or not... sounds like air or even lack of water in the system to me. What is the pressure at the pressure gauge before the boiler fires? Let me know...

Is the unit piped so you can easily purge air from the feed or retun piping? Here, you will usually find a circulator with a shutoff (or shutoff flanges) and a boiler drain above it. You shut the shutoff off and open the boiler drain while being sure that water is flowing into the system. For a successful purge try the "fast-fill" feature built into most boiler fill valves... but watch that the pressure doesn't exceed 25 PSI or you could set off the pressure relief valve (limit is 30 PSI).

To visually see the air put the hose from the bvoiler drain into a 5 gallon bucket and watch as the water overflows the bucket... should see lots of bubbles if air is the issue.

Let me know what you think...

Mark