Indirect DHW tank, how to get consistent temp?


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Old 09-02-09, 06:29 PM
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Unhappy Indirect DHW tank, how to get consistent temp?

Hello all,

I have a newly installed Lochinvar Knight Boiler model 080 (80,000 BTU) which is a mod/con along with a Lochinvar Squire hot water tank (27 gals). (Gas fired).

I have not had the opportunity to test the boiler yet as it apparently won't come on if the outdoor temp is over 60. (Well it comes on, but only tepid water comes out.)

However, the hot water tank has been a bit of a headache. incredibly, the little 27 gals has yet to "run out" of hot water, although I ocassionally ran out with my 40 gal rental. But with the new system I cannot get the water temp to be consistent. I am constantly adjusting the water temp during my shower or while doing dishes etc. (and I do mean constantly, it's very annoying).

The set point for the DHW is 120F.

Is anyone familiar with this system that has any suggestions on how to make the water temp more consistent?

Thanks so much.
 
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Old 09-02-09, 07:36 PM
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Before we get into piping, mixing valve or wiring information try turning the tank up to 130f and see what happens. I have had many issues with a 120f setting as it does not take much of a change and it feels too cool. Check a differential setting on the control. Keep it close.
 
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Old 09-03-09, 02:44 PM
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I'm gonna ask if there IS a mixing (tempering) valve installed?

If there is, what is IT set at? 120 also?

If you have a tempering valve installed and set to 120, and your tank control is ALSO set to 120, there's no point in having the mixing valve at all. If you do indeed have a mixing valve, leave it set at 120 and I would even recommend turning the tank up to 140... that way the valve has some 'headroom' to operate... and you will extend the amount of hot water available because more cold will get mixed to achieve the 120 output of the valve.
 
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Old 09-03-09, 07:24 PM
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Originally Posted by NJ Trooper View Post
I'm gonna ask if there IS a mixing (tempering) valve installed?

If there is, what is IT set at? 120 also?

If you have a tempering valve installed and set to 120, and your tank control is ALSO set to 120, there's no point in having the mixing valve at all. If you do indeed have a mixing valve, leave it set at 120 and I would even recommend turning the tank up to 140... that way the valve has some 'headroom' to operate... and you will extend the amount of hot water available because more cold will get mixed to achieve the 120 output of the valve.
AND, you will kill off legonalla bateria that just loves 120 F water temps.
 
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Old 09-04-09, 03:15 AM
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Good point trooper. The water temp always needs to be a minimum above the mix temperature.
I am confused with this Legonalla thing. I was reading an article about six months ago that was stating that Legonalla does not grow in the water heaters it grows in the piping. It also stated it cannot grow in copper pipes only steel and plastic, my assumption the article stated it does not grow in copper.
Can some one clarify? Probably should be a new subject.
 
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Old 09-04-09, 05:32 AM
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I can try.

Legionella can grow anywhere in a plumbing system. Plastics and rubber materials are favorites. It doesn't do so well in stainless, and copper actually inhibits their growth. So plastic plumbing is more prone to legionella growth. So are rubber valve seats, etc.

At 140F, Legionella dies. It grows between 68-122F, and is most prolific between 95-115F.

There's a wikipedia page that summarizes some of that info

Legionella - Wikipedia, the free encyclopedia

There is a technical article that describes some simple tests of Legionella biofilm growth on different kinds of domestic piping materials at

http://www.pubmedcentral.nih.gov/pic...1&blobtype=pdf

They took it as a given that copper wasn't very conducive to -- or inhibits -- Legionella biofilm growth (citing a couple previous studies), so they only tested a bunch of plastics and stainless in their experiments.

The various plastics showed the most biofilm growth. Partly because the bacteria can feed off the nutrients leached from the plastics, and partly because the plastics present a lot of micro-surface area because they are not manufactured perfectly smooth. Little critters love nooks and crannies....

My take-away impression is that killing Legionella in a domestic tank is a good thing, but there is still plenty of potential for downstream growth in a domestic piping system. This is particularly true in plastic piping.

Stainless indirect and copper domestic piping for me!
 
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Old 09-04-09, 07:30 AM
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I would think a chlorinated water supply would inhibit it's growth as well, no?
 
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Old 09-04-09, 09:52 AM
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Originally Posted by drooplug View Post
I would think a chlorinated water supply would inhibit it's growth as well, no?
I don't think that it does. Once inside the bio film Legionella is well protected from chlorine. IIRC, there have been studies where they found it actually has defenses against chlorinated water.

This is where heat comes into play. It does the trick in killing it.

Al.
 
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Old 09-10-09, 08:23 PM
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I set my temperature to 130 a few days ago and although the water coming out of the tap is definitely hotter, it is still inconsistent and I still have to adjust it all the time.

As for the thermal valve I did ask them to install one but have no idea whether they did. (I know they did a hot water trap like I asked them to). I can post photos of the installation if needed.

Also my tank comes on about 3-4 times daily to re-heat itself, even though I have only used hot water for the shower that morning. I hear it running when I get home from work. Would the condensate pump run without the boiler having run? It could be the pump.
 
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Old 09-11-09, 08:45 AM
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You should have a mixing valve on there. It may even be the law in Ontario. They do a great job at keeping the output temps consistent and safe.

Indirects do fire to maintain temps. Increasing the differential will minimize this but that will only make the variance out of the tank feel worse... unless of course you have a mixing valve.
 
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Old 09-21-09, 08:29 PM
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Here is a photo of my set up. Anyone see a mixing valve on there?

I have a couple of other issues too. Such as, the condensate pump is plugged into the outlet controlled by the light switch. So, it only works when the light is on (which is very rarely). Maybe this doesn't matter....?

Also over the weekend the boiler quit. An emergency after hours call produced no call back and no tech for 8 hours. The problem was a dirty flame sensor. Really? In a 6-week-old system, is that normal? The tech didn't give me an answer.

So when I call them about this I'd like to know if I should add "install mixing valve" to their to-do list....

(click on thumbnail to see full size pic)

 
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Old 09-23-09, 08:42 AM
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Question

Anyone?

Just wondering if there is a thermal regulator/mixing valve on my system?

I tried a search to see if there are any other names for it, but the search feature seems to be broken. I specifically asked them to install a thermal <something> for the DHW. I just need to know if they did or not. They installed the heat trap I asked for.

Thanks!
 
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Old 09-23-09, 09:29 AM
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there is no mixing valve visible, but some pipes cover other pipes in the pix.
 
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Old 09-23-09, 04:25 PM
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I don't see one either... it would look something like this:


courtesy drillspot.com

or maybe this:


also courtesy drillspot.com

Did they pipe the domestic lines in 1/2" ? IMHO that should be at least 3/4" ... in fact, I don't think my local plumbing inspector would allow 1/2" there... was this inspected?
 
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Old 09-23-09, 04:54 PM
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My whole house is 1/2". Would having 3/4 for the dhw make a difference in that case?
 
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Old 09-23-09, 08:21 PM
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I got 2 problems with the install, they may not have anything to do with your temperature fluctuations.
1) the honeywell / sparco powervent is on the wrong side of the system circulator along with the expansion tank and fill pkg.

This is a no no and needs to be fixed.

2) I do not see a check valve on the indirect boiler pipework, this will lead to an increase in cycling due to migration.
Now, there may be one built into the Grundfos circulator, I can not tell from the pic.

I suspect that the temperature changes are not a result of the indirect, or it may be defective. There really is no way the domestic water temps should change that much or rapidly.

There is no law in Ontario (yet) that requires anti-scald valves be installed as they require that tap temps be under 125 F. They haven't really dealt with legonela issue, hasn't killed enough people yet I suppose.
 

Last edited by NJT; 09-24-09 at 03:25 PM. Reason: changed "has killed" to "hasn't killed"
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Old 09-24-09, 03:20 AM
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What is the differential set to on the dhw? Perhaps the tank cools down too much when in use, then the boiler kicks on and gets it back up to temp. Then after the boiler shuts off, it has to wait until the tank cools down x degrees again. I'm two days using my indirect so I'm not an expert. So far the issue I have come across with mine is that first thing in the morning, my hot water isn't as hot as it should be. But after running the shower for a while, the boiler heats it up and I need to readjust. My differential was set on 10 degrees. I'm trying it at 5 to see if that helps.
 
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Old 09-24-09, 07:46 AM
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NJ trooper thanks for the pics. I do not see one of those valves on my system. The installer installed the other things I asked for (the heat trap after the DHW tank and the air separator near the expansion tank).

TOheating - can you expand on these problems you have found (maybe in a PM - i.e. can you expand on what you mean by "wrong side" - also is a check valve required when there is a heat trap?) and if you know of anywhere I can do research on this?

I phoned the company that installed my boiler and they are going to come next week to install a mixing valve and also to wire the condensate pump in correctly (currently it's plugged into an outlet that is controlled by a light switch). If there is any other issues I'd like to discuss with the company before the tech comes, and since the installer didn't know about those two issues you mentioned I don't know if they'd just take the (female) homeowner's word for it. (They have been really good and accomodating so far).

When I get home I'll measure the pipes (I think it is 1/2" but not sure), and also take a few more pictures of the setup. I believe my old hot water tank (standalone) was also 1/2". It was not inspected.... since this was a licensed plumbing company, who would I get to inspect it? Another plumber?

Thanks for the replies everyone.
 
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Old 09-24-09, 09:10 AM
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Enbridge should inspect it. Not sure about the municipality...

If you have 3/4 coming into the home which I suspect you do, you should run that to the DWH.

Anyone ever scream there about others flushing toilets while they are in the shower? The mixing valve will actually help temperature balance that a fair degree.
 
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Old 09-24-09, 03:37 PM
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Can't speak to the laws/rules in Canada... only to what I know the local inspectors will allow. And I know for a fact that our local inspector would turn all red in the face and start sputtering deleted expletives if he saw 1/2" pipes on a main line into the water heater, he might even choke on his cigar butt... or anywhere in a main line in the system for that matter. They will only allow 1/2" from a main to a fixture here... your mileage may vary.

As for inspections: In the US, before a heating system, or major plumbing work is done, the contractor must pull a permit from the municipality (and of course pay the fees $$$). This applies whether or not the contractor is 'licensed', and they MUST be licensed here... Then, when the job is complete, a code enforcement official from the municipality must come and 'sign off' on the job. Any defects he finds must be remedied by the contractor. There are 'emergency' clauses that apply, for example, your boiler takes a dump in the middle of January... you can have it replaced without a permit, but the installation MUST be followed by proper permits and inspections. If this isn't done, and a tragedy occurs... (fire, burst pipe causing water damage, etc) your homeowner's insurance company is within their rights to deny claims.
 
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Old 09-24-09, 03:54 PM
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NJ,

We are not at that level, re and re's get done with out permits all the time.
There is no obligation for us to get inspections after the re and re.
We do however (if you hold a gas licence) have to do a CO reading of the flue gases leaving an atmospheric boiler, and we red tag anything over 100 PPM.
This needs to be done once a heating season.
 
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Old 09-24-09, 03:59 PM
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Originally Posted by avatar View Post

TOheating - can you expand on these problems you have found (maybe in a PM - i.e. can you expand on what you mean by "wrong side" - also is a check valve required when there is a heat trap?) and if you know of anywhere I can do research on this?
From the pic, it appears that the air seperator, and fill pressure reg are on the discharge of the system circulator.
The should always "pump away" from the circulators suction volute.
When done this way, the pressure at the suction side of the pump remains constant and does not drop therby potentially allowing air problems.

Now if the boiler and indirect circulators pump into the boiler, then its not in as bad of place, but should be after the hot water injection point into the main loop. It will work much better there due to high temperatures.
 
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Old 09-24-09, 06:15 PM
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I specifically asked the installer to make sure the pump "pumped away" from the expansion tank since I have had so many air problem with my old boiler. (I have a diverter-tee system). I also asked for an air separator to be installed which they were not going to but did when I asked, because of the air problems. I know they followed the installation manual that came with the boiler since I printed it off the Internet and handed it to them, and I saw that they had it open and were looking at it.

The red pumps all have check valve symbols on them.



I did not see anything that looked like NJ's pics.

I will ask the city if there is a municipal inspector that can inspect the work.

The piping on the DHW appears to be 5/8" and is what comes into my house:


Closeup of pipe coming into the house:


Closeup of pipe coming out from DHW tank:


Appears to be 5/8". Is that OK?

The pipe used for heating is just a bit bigger than 1 inch.

Different angles of my system:




Does that give you a better idea of whether my pump is on the wrong side of my expansion tank? I can link you to the PDF manual for the knight boiler.
 
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Old 09-25-09, 06:20 AM
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I looked at the system more closely.

In this picture, the pipe marked in yellow goes to the port marked "inlet" on the boiler.

The pipe marked in teal goes to the port marked "outlet".

 
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Old 09-25-09, 03:05 PM
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ava, take a look at the side of the pump bodies. There is an arrow that shows the direction of flow. I believe the one on the top should be pointed to the right, the one in the middle pointed down, and the one on the bottom pointed up... that's probably the way they are, and if so, it is 'pumping away'.

As for the pipe sizes... one of those things that makes ya go 'hmmmmm' ... the outside diameter of copper pipe is around 1/8" larger than the nominal size... so 5/8" O.D. is 1/2" pipe, and 7/8" is 3/4" , 1-1/8" is 1" ...

If you've got 1/2" feeding the home, there's no point in using anything larger for the water heater I guess. Seems kinda strange that they would bring a main into a home at 1/2" ... but I suppose y'all do things a bit different up there!
 
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Old 09-25-09, 03:42 PM
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I have a question about that condensate line... you are getting the pump rewired, and that's a must, but I'm curious as to where the condensate is being pumped TO, and if there is a NEUTRALIZER on the line?

Did you say that all the pumps say that they are IFC models? I think you did...
 
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Old 09-25-09, 04:07 PM
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Originally Posted by NJ Trooper View Post
If you've got 1/2" feeding the home, there's no point in using anything larger for the water heater I guess.
Allow me to disagree agree with you on this one! L Beer 4U2
 
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Old 09-25-09, 04:29 PM
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You're allowed! Go right ahead! Beer 4U2

Of course increasing the pipe size where ever possible is gonna minimize pressure drop, if ya got a bottle neck from the street to the house, and all the rest of the pipe is 1/2", how much difference is changing a few percent of it gonna make? nil...
 
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Old 09-27-09, 09:12 PM
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Originally Posted by NJ Trooper View Post
I have a question about that condensate line... you are getting the pump rewired, and that's a must, but I'm curious as to where the condensate is being pumped TO, and if there is a NEUTRALIZER on the line?

Did you say that all the pumps say that they are IFC models? I think you did...
Technically we don't need neutralizers up here.
 
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Old 09-28-09, 02:41 PM
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Technically we don't need neutralizers up here.
Do you mean by code you don't need them?

What happens when the acidic condensate eats through the drain pipes?
 
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Old 09-28-09, 07:32 PM
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OK Really wierd... I posted after NJ Trooper and before TOHeating.. and my answer isn't there!

Basically, I said that the arrows on my red pumps all pointed in the directions specified by NJ Trooper, so I'll assume everything is set up correctly in that area... yay.....!

There is no doodad on my hose coming from the condensate pump. It looks like clear plastic tubing, and it drains into my laundry tub. I was wondering if a neutralizer was some kind of filter inside the pump housing, or whether it would be clearly visible on the outside somewhere?

Sorry bout that... my previous post went into the abyss.
 
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Old 09-29-09, 02:24 PM
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Out of habit, from time to time, instead of hitting the "Submit" button, I hit the 'back' button... and of course I end up wondering where my reply went! maybe that's what happened?

If you had a neutralizer, it would be visible in the line... it's not part of the pump... they are usually filled with marble chips, and will slowly consume the chips as they neutralize the acid. Kinda like Prilosec for your boiler... cures acid reflux. And that condensate WILL eat through the drain pipes... probably sooner than later.

I believe there is a picture of one in the manual. You can purchase one ready made, or build your own...
 
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Old 09-29-09, 05:23 PM
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Yikes! Well, better to find out now rather than later. I will talk to my installer about this when he calls to arrange to come and fix the wiring. If not, I'll learn how to make one myself.

Thanks. I hope that, plus my mixing valve I'm getting, will solve my DHW concerns.

(Yeah, I probably hit preview then forgot to submit or something...)
 
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Old 11-03-09, 06:09 PM
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safety warning

Do yourself a favor and remove the handles from the ball valves on the piping in the ceiling where they are not connected on one side before you bump into them and burn yourself. Not sure why they are there in the first place as they come off before the air seperator.
 
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Old 11-04-09, 12:37 PM
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Hi independentJC, I am not exactly certain which you are talking about but there are 2 extra valves in my piping so that I have the option to later add some radiators to my unheated basement, which would be on its own zone. So far they have not been an issue, but I appreciate the heads up.

Just wanted to update that my mixing valve has finally been installed, tank is now at 140F and the valve at 120, everything is working great now, my water temp is much more consistent.

Thanks everyone for all the help, i appreciate it.
 
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Old 11-05-09, 08:23 PM
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Originally Posted by NJ Trooper View Post
Do you mean by code you don't need them?

What happens when the acidic condensate eats through the drain pipes?
Lots of plastic pipework here, and there is so much water running thru the drains in this city the concentrations are so low.
 
 

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