I am stumped....

Mark Eatherton

And I don't get stumped very often.



I've been given the task of findingout why there are hot water shortages on a 14 story seasoned citizen housing building. THe bldg recently underwent a major mechanical face lift.



PREVIOUS system: 2 each atmspheric boilers with immersed DHW coils, a 300 gallon storage tank, and a pump moving water between the tank and the HXers in the boilers. Other than minor distribution issues (balancing of the circ return) everything allegedly worked well.



NEW system: High efficiency mod con boilers, 2 each 120 gallon reverse indirects (Turbomax) kept at 140 degrees F, and a Lawler anti scald mixing valve between the source and the loads. I performed a data logging and the DHW supply seems solid, temperature wise. The shower valves are 1966 vintage Powers model A410 pressure balanced valves.



COMPLAINTS: NO hot water in some parts of the building. Just cold, even with the shower mixer valve set for full hot. In other parts of the building, hot water temperatures are extremely fluctuating.



The C.R. ties together on the 14th floor, and goes back down to the basement mechanical room, and back to the heat source and mixing stations.



MY SUSPECTS:



1. I suspect that the new R.I DHW system and the Lawler mixing station (in series) are creating a significant pressure drop on draw, and the pressure balance shower valves are freaking out, and allowing the cold water to flood the shower valve.



2. I suspect that numerous of these Powers valves have failed cartridges in them, and are creating a cross connect between the hot and cold water lines in the risers, thereby compounding the lack of hot water.



Today during my walk about, I went to a public restroom on the first floor, right next to the mechanical room, and could not get any hot water out of a lavatory faucet (so much for the problem being confined to the pressure balancing mixers). This kind of confirms a cross connected shower valve in the risers, because I can get hot water to lav 1 in the mens room, but not lav 2, nor the two lav's in the women's R.R. The hot water supply main comes from the hall way, and runs thru the ceiling, with branches to lav 1 & 2 in the mens, then a branch to lav 1 & 2 of the womens, and then into a common riser serving bathrooms on floors 2 thru 14. When I closed the cold water branch off at the main, I got hot water in all four lavs, so again, it confirms my thoughts about a cross connected shower valve in the riser serving the bathrooms in floors 2 thru 14.



My thoughts on finding the cross connect was to shut off the cold water, and see where we still have cold water flowing (indicating a failed, cross connected valve), but with the Powers pressure balanced valve, when you shut off the cold, the hot also locks up.



I also found extremely COLD water at the top of the risers, where the C.R> begins on one of the risers.



Any have a good method (short of wholesale valve replacement) to determine where the cross connected Powers valve is at?



Thanks in advance for your input.



Baffled in Denver...



ME

icesailor

Cross Connections:

Mark,

You will have fun with that one.

Symmons mixers have the balancing spools inside the cartridge. Moen's and Kohler's are outside. I don't remember where they are on Powers. The place I honed my cross connection detective skills has a few Powers valves but I don't remember that they gave me trouble. You can usually tell if they are outside the cartridge if you slam a lav faucet and you hear a "click" behind a shower valve. They will have check stops on the valves. A bad check stop will cause a cross connection. If you run low temperatures, the shower valves won't pass hot enough water to allow the valves to mix properly. Find a cold bathroom, turn on the shower and see if it gets better. The cross connection is near bye.

Mop receptor with soap dispensers and hoses with sprays on them.The soap sales persons put those on. Abandoned showers with hoses on the shower heads are another good source.

A really great one. T&S spay units. Years ago, they had check balls. The balls get lost because someone doesn't know what they are for. The newer ones have the check in the cartridge. The check cartridge is $40.00. Without, maybe $12.00. The cheapskate, going for two replacement cartridges is quoted $80.00 for two and goes for the $25.00 value. They never wonder what that springy thing is on the old cartridge. If needed, I'll think of some more. Ive never looked for one that I didn't find. There's a valve open somewhere.



Good luck and good hunting.

And remember, it may have always had a problem. You may be looking for an old problem that they are telling you is new.

JK_3

Looking for a cross connection

Could you shut down complete floors or branches and test 1 at a time.

If I were looking for 1 cross connection shuting off the floor or riser would help narrow it down.

If susoect multiple cartridge failures then all would have to be shut down and test only one at a time,

I dont know if this is feasable but please keep us updated

good luck

Jean-David Beyer

Lawler valve data.

you may want the data sheet on your Lawler valve to see its pressure drop. And other data. If you are lucky, you can find it here:



http://www.lawlervalve.com/



I have one of their photographic valves for my darkroom and it works fine. It has two check valves, one on hot supply and one on cold supply. It has a pressure balancer followed by a thermostatic mixer. I had to rebuild it a few years ago, after 20 years of service. I suppose your main one, the Lawler one, is something like mine. Mine is for low flow rates, and works down to 1/2 gallon per minute. They make larger units. Lower flow than the minimum, and it does not regulate very well, but I never noticed crossing over.

Mark Eatherton

First response...

Chris, I've already rounded up the "usual suspects" in the building and have eliminated any obvious potential cross connects betwixt H&C including pre rinse spray hoses (none), mixing valves for public restroom facilities etc.



The pressure balance is a part of the internal cartridge assembly on these older valves. They also don't have a "maximum hot" stop setting, so thats been eliminated from the mix.



Unfortunately, these valves DON'T have integral check valves, hence the cross connections.



Cross connections within the individual units caused by shower head shut offs are a potential, but according to the maintenance director, not a real big potential (yeah, right...) Will have to institute an "Education Program" as it pertains to shower usage.



I should also note that as a part of the conservation effort that the old 3.5 PM shower heads were replaced with 1.6 GPM heads, and prior t that they didn't experience any fluctuations, but are now. I suspect the higher flow rates were masking the cross connections within the risers. And yes, I agree that a LOT of the problems were there BEFORE the conservation effort began, but were charged off to the "Well it's ALWAYS been that way" syndrome. Thanks for the input Chris.



Joe, I will be back on site today, doing additional testing. If memory serves me correctly, the local rep said if the diaphragm of the cartridge is shot, that there wold be a cross connection. Part of the problem is dealing with 50 year old gate valves on the risers. The maintenance people have been advised by local plumbers to NOT to attempt to use the riser isolation valves for fear of gate failure in the closed position. I will be attempting to verify that none of that has happened yet. The 3 or 4 valves I've exercised felt OK, but ya just never know...



I suspect numerous failed valves, based on age. Hopefully will be able to determine that on a few risers today. Guess I'd better eat my Wheaties today. Elevators are REAL old and slow, will be using the stairwells...



JD, I have the manufacturers flow/pressure drop data for the mixing stations, and at peak flows the pressure drops can be fairly significant, but this building has a fairly significant potable water pressurization system intact, and are looking at the possibility of replacement with a variable speed, constant pressure system.



Powers valves (a division of Watts companies) has always been VERY reliable, but bear in mind the age and use of these valves... Lawler has always been a solid company as well. I'm thinking I may need to get the reps for both companies onsite for a meeting of the minds.



Again, thanks to all for the thoughts and consideration. Keep the ideas coming. I will let you know what the results for the day are tonight or tomorrow.



I think I will have to re-invent the wheel as it pertains to DHW circulation return system on this job... Oventrop thermostatic control valves on the 19 circulation returns on the 14th floor, and a constant pressure variable speed C.R. pump in thebasement ought to help balance out the distribution issues, but obviously won't address the cross connection issues... Stay tuned.



ME



ME

archibald tuttle

gauging the problem?

Just to concede what I don't know right off the bat, by reverse install, do you mean the domestic water is in the coil and the boiler water is in the tank thus creating a longer piping related pressure drop on the domestic water side?  Just for my own edification, In that kind of install is the boiler triggered by flow so it anticipates, kind of like a direct water heater? What are the advantages, less corrosion to tank? Or, do you just mean that the water is coming off the bottom of the tank or . . .?



since your first theory is pressure drop across these macro elements could you jump some of that stuff out?  Assuming the two 120 gallon indirects are in series, are they piped around so you can conveniently take one out of the circuit? what about lowering the set temp to a buck and a quarter and bypassing the mixing valve?



Because this problem appears to be associated with the new installation, seems like a plausible that you actually have both scenarios going on, i.e. pressure drop across new installation exacerbating previously existing cross connecdtions.



As to actually finding the cross connections, Occasionally had these issues but maybe in 14 room building, not 14 story so . . . better you than me ?  So, I'm speaking theoretically here now and not from vast emperical experience chasing this stuff down.  What about making up some gauges with aerator thread and (assuming twin handled faucets and a helper) you could simultaneously monitor the relative pressure in the hot vs cold by being in adjacent bathrooms and turning on the hot in one and cold in another -- presumably where the pressure difference is the least is nearest to the cross connection.



And/or set up a few data loggers with pressure monitors and maybe temp probes on the water pipes behind the showers in a few places if you can get to them and see what you get after a few days of operation. Don't know how available pressure probes for those loggers are.  Been having a devil of a time getting one to operate at water column measures for steam but would assume it is a lot easier at common water pressures.



Don't know if these ideas are directly helpful, but hope they are contribution to the overall thought experiment.



good luck,



brian

archibald tuttle

pumping away

MArk,



just finished posting and saw your response.  I had thought that maybe a booster pump with recirc might iron things out a bit, although my guess is unless you could use a regulator that responded to the pressure on the cold side (which maybe is more consistent so maybe not as important as I'm thinking)  you could get hot water running into the cold side through the same cross connects?



Probably some experimentation might hit a bit of a sweet spot. This is a more adjustable version of my suggestion for dropping out some of the pressure restrictions in the hot water supply.



One other thing that occurs to me and I have no idea how complicated or expensive it would get.  IF there is a common delivery rise with a tap for each floor, could you put a check valve on the hot at each floor.  Then the floors with the worst cross connecdtions would manifest the problem without spreading to other floors.  Presumably, depending on the piping, space and convenience, you could get the 14 check valves ready and a few helpers and shut the water off and do 'em all in a day ?



Brian

Charlie from wmass

Do the Powers valves

have limit screws for high temp? I am not familiar with Powers, Symmons is king in my area for shower valves, They have a set screw. The fancier Symmons tend to lock off to cold if they are not used for a few days, I know I have 2 in Da's house. Doing it by the numbers I would say is how you will solve this. One thought is there a valve on the return piping that could have dropped a gate?

Ex Maine Doug

Use a thermal imager?

How about taking a thermal imager into the bathrooms and seeing if you can tell what is going on in the walls of the bathrooms?  One could perhaps image one that is working as a reference and go from there. 

Paul48

this way?

If you went to an apartment and ran the hot water,then take a reading with an IR thermometer on the hot side of the valve, then ran the hot in an adjacent apartment and saw a rapid change in temperature, that would probably indicate a cross-connection.Maybe a place to start.

furnacefigher15

What about

A mechanics stethoscope.



Listen for flow, at each shower valve. If you hear flow in an off valve, replace it.



I would start near the boiler room and move from there.

Weezbo

Mark

do you happen to have a recirc system on the hot side from the 13th or 14 th floor?

straight back to your water makers(Indirects?)

is there any possibility that the valves are Failing to cold?

if you tapped in with a quick fitting in the hot and ran it back in pex to the lower floor would that give you some chance to test those questions?

i think that i would look for a stuck check valve or sediments in the return side of a constant circ system .. the reason i say this is that the increased flow of the new pipe and heat exchangers may have Scrubbed the sediments clean on the new system at the mec room.....there by sending the sediments of the existing piping free clustering up working valves. i flushed the sediments at the water meter supply recently after removing the entirety of the existing pipe, the hot water maker i left in place and did not flush it ..it then jambed up the new valves so i flushed the tank and valves and it cleared...



Hope that helps.

Weezbo

*~/: )



something occurred to me , , you always do more than less, did you happen to install temp gauges in the existing C.R. and a Caleffi dirt cal prior to the recently installed Indirects?

maybe just flushing hot water out the dirt cal would clear the sediments maybe the new dedicate one tap pex recirc is over kill... i still think sediments the culprit ...

jonny88

illegal washing machine hookup?

thought i would share it with you.on a 33 floor building we service the tennants on a certain line had fluctuating hot water problems.after eliminating the usual suspects shower valves etc we found out (after 1 week of looking)an illegal washing machine.the tenant was dumping the hose out of her balcony and there we found the cross connection.another building we worked in we discovered that over the years the flappers on the check valves of the return lines would get stuck.the plumbers fixed the problem by removing the checks in trhe valves instead of replacing the whole check valve.this allowed cooler return water to enter the hot riser and gave temp problems.good luck

icesailor

Finding Things:

That's the kind of thing that can throw you when you don't do your basics.

I'm not telling you anything you don't already know but I have this job I've worked on since 1988. It was built in 1980 and was really screwed up. The heat (bridge loop crossover for the secondary drawn and installed with the return coming first, then the supply) to a Watts 2" hot water extender used as a hot water controller to control hot water temperature, In a nursing home where the hot water in the building can't be over 116 degrees, Except in the kitchen and laundry where it can be 180 degrees. All circulated to 4 wings and recirculated. Because the hot water was out of control, I thought that it just needed a new element in the N2 hot water extender. I called Tech Support at Watts and got my head ripped off by a woman engineer for installing a valve that clearly states that it is NEVER to be used as a temperature controller. :Hey, I didn't design or install it that way". What do they have? Nothing. Symmons doesn't make a thermostatic pressure balance valve for this application. I used a Leonard. They specialize in these valves. Because everything was piped 2", I bought the closest thing to what was there which was 1" in, H&C, and 1 1/4" out. WRONG!!!!!. Read and understand the valve and its application. They only work when there is high flow. The bigger the valve, the higher the flow to make them work. In this 44 bed nursing home, the proper valve was actually between 1/2" and 3/4.  The mixer I used was WAY, WAY too big. I resolved the issue by looking at the whole problem like it was a radiant floor system. I put a Taco 012 or 013 Bronze high flow circulator on the return and a Danfoss 3-way mixer so that the flow through the return always made the Leonard Mixer "think" that there was a very high flow through the valve. And when the return cooled, the Danfoss would open and allow more high temperature water to enter through the valve and keep the recirc up to temperature.

If the primary mixers are over-sized and under utilized, a perfect storm may occur.

In the "greening" of buildings, especially in renovations, The laws of unintended consequences will come forward in royal splendor. That no good deed goes unpunished.

If the tank water and system water isn't hot enough, the mixers won't work because there isn't enough hot water volume to mix with the cold to get the water hot enough for proper and designed use. Some or all of your problem may be not enough flow from lack of use or water that isn't hot enough or too cold.



Approach it like a hydronic system and it will be easier to "see" how it works and how to find it.

Weezbo

old rising stems...

something that helps open and close the older valves is backing off the pressure behind the valves .. u could go with turning of the main on a week end , draining the floors above the gate on the risers

re filling the systems that would help you get around the locking of the gate problem..

Weezbo....

Weezbo

dbl clk

i also happen to agree with icesailor in what he is saying about the temps being different enough to throw the entire existing system outta whack . sometimes the existing system is "Used to" seeing some specific water temp and with our constant vigil on the ROI we may tend to forget that the older parts and pieces may be a none to perfect marriage .. .

possibly the old valves need to see hotter water supply than may be currently allowed with the new system.



thats a Wag buh i think that is as good as any . see if that thought that icesailors got there helps get the system back in balance...

furnacefigher15

Mark

What if its simpler than that.





1. I suspect that the new R.I DHW system and the Lawler mixing station (in series) are creating a significant pressure drop on draw, and the pressure balance shower valves are freaking out, and allowing the cold water to flood the shower valve.



2. I suspect that numerous of these Powers valves have failed cartridges in them, and are creating a cross connect between the hot and cold water lines in the risers, thereby compounding the lack of hot water.





Did they also replace/ re-engineer the hot water re-circ pump? Most of the time these pumps are sized around minimal pressure drop.



I bet the new mixing station and the reverse indirect have a pretty low Cv causing the recirc to not be able to drive enough hot water into the main line. I would bet this is the trouble, if during high demand periods the problem goes away.

Mark Eatherton

Weezer!!!

Good to see your words my friend. The re-circ return does start on the 14th floor. It is piped as a split direct return (1/3 -2/3) and the balance cocks screw driver slots are failing, so most are wide open, hence the distribution issues. According to the manufacturers rep, if they have a blown diaphragm, then they will cross connect. He's coming out Monday.



We've power purged the returns as well as we can given the balance cock issue, and haven't seen much gun coming out of the system.



Unfortunately (or fortunately depending upon your perspective) I didn't actually do this work. I was called in to figure out why they have been having so many issues this last 6 months. Lots of irate seasoned citizens in this building. The poor installing contractor has worked her butt of trying to resolve it to no avail.



Stick around won'tcha?



Welcome back.



ME

Mark Eatherton

Reverse indirect information...

http://www.thermo2000.com/content/en-US/s2_produits/optimizer.aspx



They have two 119 gallon tanks piped in parallel, and they are in series with the Lawler mixing stations. THey normally only run one mixer at a time. Yesterday I opened up both to see if that helps. The agency that paid for these changes has been a student of mine for many years, and with seasoned citizens, I always recommend maintaining the storage tank at 140 degrees F plus, and mixing it down to around 130 degrees F to avoid water borne bacteria, primarily Legionella. The tanks are all copper on the potable passages, so it is a natural anti bacterial material, and we may have to bypass the mixing stations to se if that helps, but only as a last resort.



We tried lowering AND raising the temperature, and it does not appear to have any affect on the shortages.



Generally speaking, the Powers valves are intended for use in areas with pressure differential between the hot and cold, hence the pressure balancing spool feature of the valve. They were designed specifically for this type of application. Its just when the pressure differential diaphragm blows that they become a problem.



Unfortunately, I don't have any data logging pressure sensors, and would have to have 28+ of them to do a decent survey, and the agency is not willing to foot that bill.



All ideas are helpful. Thanks for the input.



ME

Mark Eatherton

Charlie....

These 1966 valves didn't have the MAX TEMP adjustment screw. Some of the replacement cartridges do have an adjustable stop, but based on my experience yesterday (saw 26 bath tub faucets) none of them are being used. The only gates are at the very bottom of the system and they serve branches that serve bath/kitchen riser group.



Thanks



ME

Mark Eatherton

The problem with thermal imagers and copper/brass piping...

Hi Doug, That thought crossed my mind, but the emissivity of brass is such that it doesn't show hot or cold. I could use the software that comes with the camera, but couldn't make a determination in the field. As I said, I saw 26 shower valves yesterday in the worst column. I was running hot water in the public restroom at the base of the offending stack, and could only get cold, so went into emergency viewing mode and went up through the column checking the tub faucets for anomalies. I found two (2) valves on the 7th and 8th floor (roughly the very middle of the riser) that had ICE COLD stems. Unfortunately, neither of the isolation valves for these units would work, so I couldn't do a failed valve test on them. Will go back Monday, isolate the complete riser and replace (hopefully) the guts of the valve and see what kind of response it gives us. Just for the record, I will take some IR pictures of good and bad to see how much difference it shows. Thanks for the thoughts. Great minds think alike ;-)



ME

Mark Eatherton

Screw driver to the head bone...

I was listening to the risers as I was going up through the column yesterday. I could hear water running, but I was running water at the base of the stack in two lavatories at the base of the stack. I thought about borrowing my friends electronic leak detector which allows you to see sound as a percentage, but he's an hour and a half away. May have to follow through with this idea if all else fails.



Thanks



ME

Mark Eatherton

Illegal washers..

Dish and or clothes washers were not seen during my visual inspection yesterday. I've been assured that NO ONE has one in the building. I eliminated that as a possibility early on during my preliminary review.



Thanks



ME

Mark Eatherton

RS and Y valves...

My thought is to replace the bad gates with ball valves, but even ball valves fail if not used on a regular basis. Valve exercise program? Whats that? We don't need no stinkin' valve exercise program!



You are correct that equalizing pressures allows the valve to open easier. Denver Water uses a cross over between the two sides of the gate to equalize pressure prior to opening or closing the vale. Replacing a 36" gate valve takes a little longer than doing a 2" valve... Especially when its 8 ' below grade.

Mark Eatherton

Old system....

The old system had a completely different pressure profile, and as I have stated, I may have to eliminate or bypass the mixing station. When I get involved in problems like this, I ask myself "What's changed?" The old system had VERY little pressure drop on flow because of the storage tank/heat exchanger combinations. I may have to replicate the old system to make the problem go away. Either that or replace a WHOE bunch of shower valves, which is not in anyones budget.



All of this is a learning moment for everyone involved, and if we are paying attention, will WILL learn from this experience. As Chris stated, going green does have its consequences. One has to look at the building as a "system" to se what happens if you do THIS, and what affect its going to have on THAT. One thing for certain, in our mechanical reviews that are performed for this state agency prior to funding, there will be a whole new section on the DHW side that looks at the make and type of shower vales, as well as any "issues" the existing system is experiencing. Putting a larger pump on the circ return may cause other consequences of imminent nature, that being hydraulic erosion of the mains and return lines.



We are ALL still learning, and I hope that other people benefit from my problems. I appreciate the fact that Dan and TLM have given us the opportunity to utilize this forum to help us out. Thanks to all who participate, and especially Dan and TLM for making it happen.



Live, and learn.



ME

Mark Eatherton

I wish it were that simple....

The pump is existing. I am thinking about re-engineerng the system as follows;



Due to the fact that the system is piped direct return (split in 1/3 - 2/3 configuration) it is difficult to balance out. I feel we need about 1/2 GPM per riser to maintain good constant hot water availability. there are 19 C.R> riser in the building. I found an Oventrop two way brass valve that accepts an Oventrop remote capillary tube controller that can be set to control the valve based on pipe temperature. I figure I will set them for 120 degrees F, and when the sensor see that, it will shut the valve down.



Based on conversations with the residents in the worst riser group yesterday, hot water is more readily available during NON peak hours (midnight to 6 AM) rather than during peak conditions. I know, doesn't make ANY sense, but a cross connection scrambles the brain...



As for the pump, I'm thinking that I need to set a bronze, constant pressure, variable speed circulator to move the water throughout the system. This will keep hot water readily available at all points of use without creating major pressure differentials. As the valves close, the pump cycles back. I will have to recalculate the pressure drops through the mains and the return mains, but I do have a full set of blueprints to make that task easier.



Who knows, I may be reinventing the way we do DHW CR systems... :-) It's about time we change the way we've been doing things.



Stay tuned, and thanks for the input.



ME

Mark Eatherton

Update...

Yesterday I tried doing some different things in an effort to get these people hot water.



1. I moved the false PONPC (potable water expansion tank) to the C.R. pumps inlet. It did cause the CR pump to generate positive pressure as opposed to negative pressure, but didn't seem to make much difference n the availability or cross connection.



2. I found that I had cold (COLD, like 45 degree F) water making it back into the return from the offending riser. I closed that balance cock off, will see if that made any difference over the weekend. Pressure flows from high to low, even though both sides are pressurized from a pressure boost station. But the circ return pump shouldn't compound the cross connection problem because there isn't any where to move the water to... I suspect failed valves on the supply side, and some risers getting their hot water from the circ return. Going to require more in field investigation. Gotta eliminate the big ducks first, and then fall back and regroup.



3. I went all the way through the worst offending risers bathroom groups, puled the face off of the shower valves, and performed an Ooohh Ahhh touchy feely test on the hot and cold connections to the shower valves, all while I was running hot water (actually VERY COLD water) at the lavatories on the main floor. I found two valves, one on the 7t floor, and one on the 8th floor that had EXTREMELY cold stems coming out of the wall. In some cases, I was able to close the cold isolation valve, and when I opened the Powers valve, got no flow. This, I am told by the rep, indicates the diaphragm is not failed. If it is failed, the valve will pass water with one half turned off. Unfortunately, I couldn't isolate the two offending valves, and will have to shut off the water to the building in order to replace the cartridges on these two valves.



4. I did a pressure drop test across the RI's and the tempering station, and it was nil differential (about a 25 PSI drop, but was the same at the inlet as it was at the outlet, hence no differential) meaning that the mixing station (Pressure Balance anti scald) was seeing the same pressures at the hot as well as the cold.



5. I confirmed hot water at the top of the system, and conformed that the cross connect in the offending stack riser was making it into the returns, as well as the supply. Makes sense based on pressure differentials on draw.



Hopefully we will get most of our problems resolved come Monday when the reps for the valves (Lawler and Powers) show up.



Thanks to all for their input to my problem and stay tuned.



Headed out for some rodeo action at the Stock Show. Watch yer step. YEE HAAWWWww.



ME

furnacefigher15

Mark

"Based on conversations with the residents in the worst riser group yesterday, hot water is more readily available during NON peak hours (midnight to 6 AM) rather than during peak conditions. I know, doesn't make ANY sense, but a cross connection scrambles the brain..."



This complaint does make sense for cross contamination problem. There is less pressure difference between the cold and hot water during low demand periods, especially with a restrictive mixing station.



I would tend to think that if the whole riser is effected, the trouble starts at a low point, rather than a high point.



My logic on that is based on the pressure drop of the piping, and the laziness of water.



I would think a cross contamination high up on the riser, would have a greater effect on the upper section, then on the lower, because it would be easier for the hot water to flow from the basement, instead of the cold all the way up through a valve and back down.



But, you never really know.

Paul48

approach

Start from square one. You seem to be chasing the effect.Look at the system as it is now, and verify it has everything it should have. Then ask yourself, what would be the affect of one of the components not working correctly. Take the mixing valve out of the equation, for the time being. It can't add cold water to the system while in re-circ only anyway,only on a pressure drop from a fixture being used.

tim smith

Re cold water out the hots etc etc

We had the same problem in a 21 story building about 8 yrs or so. Found that the balance valves for the stacks had gotten so far out of adjustment along with one riser blockage was effecting appx 10 of the 70 or so units in building. My buddy (plumber) spent appx 16 hrs in there flushing out the returns and setting balancers. This all happened after a pipe lining company relined pipes. But said ohhhhhh no, we did nothing??? 

icesailor

I think you found it:

Those shower valves you found that are cold? They are the culprits. They and others like them. Like I said earlier, Symmons type have the spool in the stem. They are positive shut off valves. When the valve handle is turned off, there is a 100% positive shut off in the valves. Older Moen's, Deltas and the Kohler Rite Temp type have the spools outside the shut off and there is a direct cross connection between the hot and cold at all times, regardless if the valve is off. They depend on the check stops. Leonard valves are used for hot water temperature control. They depend on the check stops. And if you try to service a valve, and the check stops don't shut off the water, it can and will cross flow. One passing valve will screw the pooch.

And watch out for janitors closets with mop receptors with hoses connected. Soap sellers like Ecolab put automatic soap dispensers on the hose fitting so that mop buckets can be filled. If there are no check stops on the H&C, and the valves are open with a hose turned off, there's a cross connection. Or, like I said previously. The wrong cartridge is installed because the correct one is more expensive, I see it with T&S all the time. Where I work, it is a restaurant capitol. I always see restaurant maintenance people coming in got T&S stems. My supplier doesn't stock the ones that fit the Pre-Rinse units that need the check stops. They get used to having cold water coming out of the hot water for years. If you want the correct ones, they bring them from Central Distribution on Tuesday.

Mark Eatherton

Update...

I had the maintenance man replace the cartridges in the know defective units on the 7th and 8th floors today.



We had hot water everywhere it was supposed to be, and DIDN'T have cold water where it WASN'T supposed to be.



I'm not confident we are out of the woods yet, but this is progress that has not been seen before.



We are going to let the building run for a few days, and then survey certain problem area residents and see if the results are better. I am hopeful that the MAJOR issue has been quashed. I suspect that there are other issues still in the building, but time will tell.



Thanks to everyone for their input.



Your assistance has been, priceless...



Mucho Gracias ;-)



ME

icesailor

Stumped:

I'm not saying "YOU" Mark, but a lot of you "Heaters" have no realization of the concept of how much potable hot water water can be lost by a by-passing hot and cold water valve. I have been diagnosing it for years. It can become VERY expensive for a customer who hires a "parts changer" to solve the problem. You are not a parts changer. You took a balanced approach to the problem and solved it. You look at 180 degree water with a 20 degree drop at whatever GPM. Plumbers look at 55 degree water and raising it 100 degrees with varying GPM's. That's why so many systems installed by "heaters" who don't have the understanding, have poor hot water performance.

There is no worse scorn like a woman in the shower with cold water, soap in her hair and late for work.

Those type of valves should have spring checks as part of the positive shut-offs for the valves in building like that. So you don't have to shut off the whole building to service a valve.

Make sure that the maintenance person gets check stop repair kits for the effected valves. If they were OK, you wouldn't have the problem.

Congratulations. 

Mark Eatherton

Update 2...

The saga continues... We are finding that there are MANY bad, cross connected cartridges in this system. We found 6 today in just one riser. Slowly but surely, we are picking off the biggest offenders, and getting the system cleaned up. The previous stack that we did is working FANTASTIC.



2 down, 2 to go.



FYI, we have found that the best way to find failed cartridges is to remove the face of the valve, run it until it gets hot, then run the hot in the lavatory next to the tub, and if the hot side of the valve goes cold, it has failed. As a means of back up and confirmation, where possible, close one isolation valve (hot or cold) and attempt to draw water through the shower valve. If it locks up, the cartridge is OK. If it spills water, it is blown. Once pulled, if you can blow air through the cartridge, it is definitely shot.



More fun tomorrow and Monday. Hopefully by Monday, we will be completely done and the seasoned citizens will have to find something else to complain about :-)



ME

icesailor

Check Stops:

And one or both of the check/stops in the effected valves have failed.

If you are in a pinch, take the cartridges/ balancing spools out and soak them in white vinegar for a few hours. It will clean the crud out to like new condition. Clean some of the old ones for emergency spares.

Mark Eatherton

No check stops...

This is a circa 1966 vintage debacle, and there are no check valves in the shower valve body. If there were, and they were functional, we probably wouldn't be having this conversation :-)



ALso, the pressure balancing diaphragm is in the body of the cartridge assembly, and if it is blown, its trash. No amount of white vinegar will help at that point, but I understand what you're saying.



Thanks again Chris.





ME

Mark Eatherton

Situation resolved...

The front office receptionist told me yesterday that her telehone had quit ringing, and that all of the residents "smelled real good and clean".



I still have some "issues" to work through with the property management folks, but all cross connected valves have been located and repaired. Hot water for everyone.



Thanks a million to all for thier help. My PC is in the shop being repaired, so I can't deliver a copy of the letter I generated to help others with Powers shower valves to locate blown cartridges, but as soon as is gets back form teh PC hospital I will post it here..



ME

Kevin_in_Denver_2

Copper behind a wall

You're looking for a warmer stud bay. Since the wall isn't copper, you could "see" that.



BTW on bare pipes, you can use cheap flat white or black spray paint to fix the shinyness.

Alan (California Radiant) Forbes

Super Sleuth

Way to go, Mark.  Frustrating work, but satisfying when you reach the other side.  Now you get to collect.

Mark Eatherton

Thanks Alan...

Here is the letter I generated.



ME

Mark Eatherton

If only it were that easy Kev...

If all I were looking for were pipe chases, your idea would hold water. However, I was physically looking for cross connected valves. It ends up, that the brass valve bodies had enough corrosion on them (1966) that the emmisivity was perfect for the IR camera.



Attached find IR photographs of the good, the bad, and ugly. Valves that is...



Per the instructions, we had to pull the valves face plate off to be able to see the actual valve body, but that was the EASY part. Getting good water isolation proved to be much more difficult.



Enjoy!



ME