Lochinvar KBN150 with sidearm losing capacity to heat DHW ?

moots

Hello:

I am a DIY and have a Lochinvar Knight KBN150 with a SSS041 Indirect Gas fired water heater. I have noticed over the last couple of months that the DHW for a shower does not have the capacity that it used to. Showers require a maximum setting on the valve body to maintain a warm flow.

Nothing has been changed on my setup, the outside and inside temp readings from probes are accurate, the boiler is set at 180, the DHW is set at 140 which I just adjusted to 150 to see if that helps.

The DHW output to the house gauge reads 140 initially and slowly drops to 130.

Am I slowly losing a Taco mixing valve for DHW or is the sidearm slowly going bad ?

Where should I start checking first ?

thanks!

Dave

hot_rod

Indirect, but not gas fired is probably what you have?

How long has the system been in operation? What is you water hardness? How about indirect operating temperature?

All these factors combined with how much hot water has run thru the system tells the story.

In some cases thermostatic valves need to be de-scaled yearly.

Higher DHW tank temperatures add to the de lime frequency.

Indirect tanks can also scale up and performance drops, especially on the higher operating temperature systems.

I think thermostatic mixing valves should be installed like tankless water heaters with isolation/flush valves.

Here is another method for de-liming, as some valves are no longer able to be field dis-assembled or rebuilt. I use a tankless cleaner kit and pump the acid thru the 3 way valve for 20 minutes to clean they out.

Or replace the valve, clean the old one for a spare next time it scales up.

moots

Hi Hot Rod:
Indirect, but not gas fired is probably what you have?
correct

How long has the system been in operation?
9 years

What is you water hardness?
Hard water for sure, Mountain House in Colorado

How about indirect operating temperature?
Boiler was set to 140 DHW, just changed it to 150 to see if it helps


So I you think the Taco 5000 has issues with scaling ? The setting on the valve has been always set to MAX..output gauge just beyond this reads 140 and settles at 130. Scaling reduces the efficiency of the valve and degrades flow sounds like ?

Perhaps I should flush the tank as well ? Have never done that but seems easy enough ?

thanks,

Dave

Jamie Hall

Never flushed nor descaled the tank? On hard water? Uh... yes, that's where you need to go, along with the mixing valve.

moots

If I have never flushed the indirect tank it may not be a good idea to do so now. I have read where loosening all the sediment and debris after all this time may in fact cause a leak ?

Perhaps I am mistaken since this is not a gas fired water heater ?

There is an cold inlet on the bottom of the tank combined with a drain. I am guessing to shut off the cold supply and open the drain hoping the residual tank pressure is sufficient to drive the crud out ?

flat_twin

Your first comment is that the shower is barely hot enough even when turned up to max. You also said your temp gauge says 130 degree water is going to the house.
You might want to check your shower mixing valve. 130 degree water is plenty hot and you would be mixing cold water to make it tolerable. Can you duplicate the barely hot water at the bathroom sink? Elsewhere in the house?

hot_rod

What brand and model is the tank? It would be nice to know if it has a smooth or finned coil inside.

Flushing will remove loose sediment that has collected, sometimes the coils them self get a thick coating and need to be de-limed with an acid based cleaner. Start with a good pressure flush, then check performance of the tank.

Somehow it would be nice to flow backwards thru the tank so the drain could flush out better. If you flow cold in the same pipe that you are trying to flush crud out, you may not get much result.

Some plumbers attach a small tube to a hose and reach down inside from the top hot port to flush out stuff from the bottom better.

If you are really lucky the tank could have a hand hole that you could actually remove and reach inside to scrub it out.

With a mixing valve the scale prevents the cartridge inside from moving up and down freely, and regulating accurately, may as well clean it or replace the cartridge while you are at it.

9 years on a tank with unsoftened Rocky Mountain water, hmmm

moots

Flat_Twin

The water is plenty hot everywhere in the house including the shower, modifying my earlier comment. The issue is it requires a max setting on the shower valve after a few minutes to maintain a warm flow, not hot.

I will try the other shower in the house..could be a clown move on my part if the shower valve which is 18 years old is toast.

flat_twin

Where is your temperature gauge? Before or after the mixing valve?
If it's happening at every faucet I would just sit by the boiler and indirect while someone takes a nice long shower and see where your temperature drop occurs. See how long the indirect takes to recover.

Are the domestic cold and hot water pipes on top of this indirect?
A broken dip tube will cause this too. You get a few gallons of hot water but it gets cooler because it's pulling cold water

delta T

What kind of shower valve do you have? If you have a thermostatic shower valve you may need to descale the mixing element in the shower valve as well or maybe even replace it.

moots

Apologies for not posting the correct symptoms thus far, here is the NEW information for you experts:

The DHW is working perfectly on the 1st floor of the house.

The 2nd floor faucets, tub and shower all exhibit the same symptoms. Initial call for hot water is fine but tapers off after a minute or so. If you shut off the fixture and turn on again, for a few seconds you get HOT water.

I now suspect a circulation pump ??

The main DHW pump connected to the Indirect Water Heater is a Grundfos which is on the HI setting per a switch, Model #UPS-26-99 non submersible circulation pump. On the Lochinvar Boiler display it shows it ON and I can hear it SPINNING UP when called for but the display says 0-10vdc and the IN parameter says 0.0v. According to the manual this only show voltage when connected to a Building Management System.

The Taco Cartridge Circulator Model 006-BE4-1 is HOT TO THE TOUCH as always, this is plumbed in downstream. When I put a screwdriver on it and the handle on my ear I cannot hear anything !
Can I check the pump by removing the four screws and having a look ?


thoughts ??

Thanks experts!

Zman

I think you may have a hot/cold cross connect.
Did you recently add a handheld shower head with a valve on the head?

moots

Zman:

The only thing I did a couple months ago was tap into the H/C domestic lines and extend them to a new laundry room washing machine and sink. No symptoms in this room. Why would this not be symptomatic of the entire house ?

rick in Alaska

That Taco 006 pump is recirculation pump that circulates the hot water back to the indirect? It might be possible that the check valve is stuck in a partially open position. The easiest way to tell would be to feel the pipes just before the pump, and then have someone run a hot fixture.That pipe should not go from hot to cold right away.That would be a sign of a stuck check valve.
Do the same procedure with the line leaving the mixing valve off the indirect. See if that line drops temperature at the same time the fixture is losing temperature, and do the same test with the line leaving the tank. If both of them stay hot while the fixture is cooling off, then you know it is in the house piping, not the water heater circuit.
Rick

hot_rod

moots said:

Apologies for not posting the correct symptoms thus far, here is the NEW information for you experts:

The DHW is working perfectly on the 1st floor of the house.

The 2nd floor faucets, tub and shower all exhibit the same symptoms. Initial call for hot water is fine but tapers off after a minute or so. If you shut off the fixture and turn on again, for a few seconds you get HOT water.

I now suspect a circulation pump ??

The main DHW pump connected to the Indirect Water Heater is a Grundfos which is on the HI setting per a switch, Model #UPS-26-99 non submersible circulation pump. On the Lochinvar Boiler display it shows it ON and I can hear it SPINNING UP when called for but the display says 0-10vdc and the IN parameter says 0.0v. According to the manual this only show voltage when connected to a Building Management System.

The Taco Cartridge Circulator Model 006-BE4-1 is HOT TO THE TOUCH as always, this is plumbed in downstream. When I put a screwdriver on it and the handle on my ear I cannot hear anything !
Can I check the pump by removing the four screws and having a look ?


thoughts ??

Thanks experts!

Yes, remove and check the recirc pump. It should not be much hotter that the temperature of the water going thru it. You need to isolate with valves of course before you remove the 4 bolts.

SteveSan

It's rated to go to about 220F, you must isolate the pump and remove the 4 bolts. Once you take the motor away from the casing you can do a bench test to see if the imp is spinning. If not then you need to replace the cartridge. You may also have some debris around the imp check for that. The replacement cartridge is 005-020RP. You can also take an amp reading on the motor.

moots

So the Taco 006 sources cold water and pipes out to a fixture on the 1st floor. When disconnected from power it quickly goes from too hot to touch to cool.

When hot water is called for the inlet goes cold immediately as does the output. Isn't this correct since I am sourcing cold water ?

moots

General question:

Would a fault 006 cause my symptom of 1st floor all good and 2nd floor hot water fades after a minute or so ?

moots

I also have a 200 WOG design Check Valve in a different part of the cold water supply, perhaps this is the real problem ??

flat_twin

moots said:

General question:

Would a fault 006 cause my symptom of 1st floor all good and 2nd floor hot water fades after a minute or so ?

It's possible your first floor bathroom /kitchen hot water faucets etc are working OK because they're piped directly from the dhw mixing valve near the indirect with no recirculation loop.

Your upstairs bathroom is so far away from the indirect water heater it would take several seconds, maybe a full minute for hot water to reach the upstairs bathroom. So, it was piped with a recirculation loop which circulates hot water to and from the upstairs bathroom (continuously or on a timer) for the sole purpose of having hot water available as soon as you open the faucet. Your problem is with the pump, check valves or other components of this loop.

Zman

moots said:

Zman:

The only thing I did a couple months ago was tap into the H/C domestic lines and extend them to a new laundry room washing machine and sink. No symptoms in this room. Why would this not be symptomatic of the entire house ?

If the problem started when you installed the sink, it is very likely the cause. Does the sink by chance have a hose and valve attached?
Try turning off all the stops in the sink area and see if that solves it.

moots

Zman:

Not sure if the problem started then but the sink is not yet installed, just roughed in and the washer isd connected. I shut off the valves on the washer just to see if that affected anything. Don't think it's related just by adding 10 feet to each H/C line. Bought a new Taco cartridge but maybe I have just reached the limits of the pumps ability, who knows.

hot_rod

Just to be clear that recirc pump just maintains the temperature in the DHW loop, it does not supply the water flow to the fixtures. The water pressure in the system "drives" the water to the fixtures

Recirculation assures you get hot water quickly to all the HW fixtures, by maintaining the loop at 120F, or whatever the mix valve is set to.

With a recirc, the mix valve needs to be piped a specific way to prevent creep, or droop in loop temperature.

Is it possible some of the HW fixtures are on the recirc line, others not?

Kinda need a drawing of how it is all piped. If it has worked properly in the past, and the issue is temperature fluctuation, I'd suspect the mix valve. If the wait for DHW is the issue, I'd look at the recirc pump. Assuming nothing else has changed?

Single handle tub/ shower valves can sometimes cross H&C, a tougher problem to track down.

moots

Hi Hot Rod:

Good news and bad news:

So I replaced the 006 cartridge and it was completely seized up, scaled etc so that's the good news.

The way it was plumbed is there was a shutoff valve just after the pump on the return to the cold water but nothing on the side from upstairs so I was unable to totally isolate it. After installation there is really loud noise coming from the pump. Thinking there is AIR in the line/pump that I cannot eliminate without installing a "T" and a DRAIN between the pump and the shutoff. I also tried the trick of turning the valve off and loosening the bolts on the pump to DRIVE out the air but it keeps blowing off the O ring and floods.

Guess it's possible I have a bad pump as the GFCI it's attached to trips after a couple of minutes or that's simply protection for pulling too much current.

Think the whole pump needs to go or is there air making that noise for the entire house that is the issue ?

thanks!

hot_rod

You need a strategically positioned purge valve, or two to get all the air out of that recirculation loop.

If you install one of these Webstone valves you can purge from both directions. It can take a few minutes to adequately purge a long loop.

Close the valve and purge the pump out, flip the handle and purge from the other direction to get the loop air free. Assuming there is no check valve in the pump or system?

Use a wash machine hose in a 5 gallon bucket to see when all the air is purged out.

moots

Hi Hot Rod:

Well I have discovered the cause of the noise from the 006:

Upon taking it apart (for the 4th time arghh), I discovered the housing where the impeller sits to recirc the water is scarred from the impeller. Not sure if it is from the new cartridge or old but by backing off the mounting bolts a couple turns on all four I immediately changed the noise to tolerable. I am afraid to unscrew any further for fear of the O ring blowing off and leaking. I have created a very small bit of space between the flange and the housing. I did notice when removing the original cartridge that the bolts were not that tight!

Instead of sounding like a small hammer drill it now is mostly light noise which I can change by retightening the screws to bring back the original unacceptable noise!

Have you ever run across this issue ? Seems like something is out of tolerance and I should probably replace the whole thing but going to see if it eventually grinds itself down maybe 1/64" and I am guessing the problem goes away.

That being said the pump is probably 20 years old lol....

thoughts ?

hot_rod

moots said:

Hi Hot Rod:

Well I have discovered the cause of the noise from the 006:

Upon taking it apart (for the 4th time arghh), I discovered the housing where the impeller sits to recirc the water is scarred from the impeller. Not sure if it is from the new cartridge or old but by backing off the mounting bolts a couple turns on all four I immediately changed the noise to tolerable. I am afraid to unscrew any further for fear of the O ring blowing off and leaking. I have created a very small bit of space between the flange and the housing. I did notice when removing the original cartridge that the bolts were not that tight!

Instead of sounding like a small hammer drill it now is mostly light noise which I can change by retightening the screws to bring back the original unacceptable noise!

Have you ever run across this issue ? Seems like something is out of tolerance and I should probably replace the whole thing but going to see if it eventually grinds itself down maybe 1/64" and I am guessing the problem goes away.

That being said the pump is probably 20 years old lol....

thoughts ?

I'm not that familiar with the 006. Maybe it had an aftermarket cartridge added at one point that was out of tolerance? I suppose you could take a file and trim the high spot.

moots

Thanks Hot Rod I am going to start a simpler Taco specific thread on the main wall now that I sort of know what I am doing.

Thanks to everyone on this thread for their assistance!

It's not even about saving money as I like to know how things work being an engineer, since I know enough to be dangerous on Hydronic systems the help was really appreciated!

Dave