Hot Water Ciculator Always Running


  #1  
Old 06-02-21, 04:52 AM
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Hot Water Ciculator Always Running

Good morning everyone,

My hot water circulator has been running for almost two days straight. The hot water heater aquastat keeps it running unless i turn the dial to its lowest setting, then it shuts off.

I suspect the aquastat is the suspect, calling for heat when it shouldn't? the boiler is at 170 or so and turns on when temp drops enough so i don't think the issue is the heating.

thoughts?



 
  #2  
Old 06-02-21, 02:10 PM
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G,
It sounds like you have an aquabooster which is just a storage tank for the hot water made from your tankless coil in your boiler. What this tank does is give you extra hot water supply because your tankless cannot keep up with demand.

Your problem could be a bad aquastat possibly caused by a bad sensing bulb or it could be caused by the tankless not delivering enough hot water to the tank due to mineral buildup in the tankless coil in the boiler. Even though your boiler aquastat is operating properly does not mean your boiler coil is.

Are you getting sufficient hot water as you were before this started happening. You have 2 oipes going from your coil to your tank. Feel the supply pipe from the coil to see if it is hot going into the tank. If it is not hot then the problem is with the coil and may be time for a replacement or at least getting that one cleaned.

The thing to remember with storage tanks or aquabooster tanks is they will only store what the tankless coil is able to produce.

Hope this helps a little.
 
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Old 06-02-21, 07:44 PM
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I have an indirect water heater, setup as a separate zone. The water in the DHW circulation loops is very hot, just that the circulator never stops.
I ordered a new aquastat, may try to remove and clean the existing one as well to see if that that helps.

thank for the info!
 
  #4  
Old 06-02-21, 11:01 PM
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How is it set up for a separate zone..... some type of zone controller ?
Do you have zone valves ?
How many circulators ?
 
  #5  
Old 06-03-21, 09:08 AM
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I have circulators, one for zone 1 - whole house and zone 2 is hot water. left zone (3rd is not used, heating for an attic that's not in use)

Took out and cleaned the sensor probe and sunk it deeper into the well, so far no change.
Also ordered a new aquastat, will replace tomorrow once it's in to see if that's the culprit.

 
  #6  
Old 06-03-21, 12:12 PM
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A simple way for GeneBerg to check aquastat is to loosen screw on clamp right side. Then remove aquatat from water tank.

Make it easier to see when pump has powered with 120 volt pilot light wired to it. https://www.ebay.com/sch/i.html?_fro...+wire&_sacat=0.

If when removed and cooled circulator does not shut off aquastat is has problem.

If pump turns off aquastat bulb is bad.

Next remove 2 phillips screws and remove micro switch.

If pump keep running replace switch. While micro switchs look similar there a significant difference is activation travel. Look for part number on it.
 

Last edited by doughess; 06-03-21 at 01:08 PM.
  #7  
Old 06-03-21, 03:53 PM
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G,
This may be a little off topic and of interest only to you. You mentioned you have an Indirect HWH on its own zone but you posted a pic of a tripple action aquastat witch has a high & low limit and maintains temp all year long. Generally those controls only come with boilers that have tankless coils.

The way that it is set your boiler is maintaining temp all summer even when nothing is calling. If you have an Indirect HWH you can either turn down your LO LIMIT to around 100 or disable it altogether so that the boiler only runs on demand for heat or hot water and save a little fuel. This is called a cold start boiler.

This is just a thought in case you were unaware of the difference. What you have now is called a warm srart boiler because it never shuts down.

Is it possible to post a pic of your Indirect HWH just for curiosity sake.
 
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Old 06-03-21, 06:17 PM
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The aquastat on GeneBerg's water heater is high limit which opens circuit at set temperatue. It is a simple on off switch, not a triple action, high & low limit control. When switch contacrts close, it only activates the circulator and does not directly control boiler/burner.

DH prior #6 post suggested simple steps to to isolate problem

After GB confirms aquastat is OK, he can consider other issues. Maybe there is short in wiring that causes circlator to run, or someone left hot water faucet open?

Good trouble shooting technique is checking basics first before going on to the esoteric.
 

Last edited by doughess; 06-03-21 at 09:04 PM.
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Old 06-03-21, 08:42 PM
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Thanks everyone.
the aquastat was getting 120v, i checked with a multimeter before removing it. The circulator turns off when I turn the temp down to around 100 - 110 at the aquastat so it may be reading too low of a temp in the storage tank. cleaning didn't help

The variable speed circulator is for the primary house loop, hot water is pumped by the Taco circulator in the middle.

Full pic attached, it's a panoramic shot so a bit skewed

 
  #10  
Old 06-04-21, 08:31 AM
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Well, replaced the aquastat and we're back in business

Regarding the temp setting, generally i turn down the Hi/Lo limit to 130/150 during the summer and aquastat down to 120 or so vs 140 in the winter but the boiler does run all year as a warm start.

I use around 0.6 gallons/day to maintain its temp and keep 40gal tank hot.
 
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Old 06-04-21, 12:49 PM
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Doughess,
Another good troubleshooting technique is to read the whole post and look at all the pics before rushing to comment on something that has nothing to do with a post you're commenting on.

The aquastat that I was describing was on the boiler and was accompanied by a pic of a triple action aquastat but it's always nice to know big brother is watching out for us less fortunate souls who do not have your vast knowledge.

Believe it or not there are people on this sight that have survived before you gave us the privledge of your expertise.

Enough said!!!!!


G,

You can disable your LO LIMIT if you want. It has nothing to do with keeping your Indirect hot. That runs off your tank aquastat when needed which starts the boiler and then the boiler shuts off on HI LIMIT when reached. The lower you turn the temp down on your boiler the lower the hot water will be in the tank since the boiler water is what heats the cold water fed into the tank.
 
poorplmbr voted this post useful.
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Old 06-04-21, 09:09 PM
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DH Post #6 & #8 were about Post #1 Text and top picture was of it.
The hot water heater aquastat keeps it running unless i turn the dial to its lowest setting, then it shuts off. “
DH Posts were specific and direct response to water heater aquastat.

GeneBerg then posted
Well, replaced the aquastat and we're back in business
Do know know which posts GB read but a least someone is happy.
 
  #13  
Old 06-05-21, 10:14 AM
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Thanks for your help everyone.
Regarding the low limit setting, I've read rumors that you shouldn't let the boiler cool off completely as it'll spring leaks, etc..if allowed to drop down to a low temp.

Any truth to that?
 
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Old 06-05-21, 10:45 AM
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Regarding the low limit setting, I've read rumors that you shouldn't let the boiler cool off completely as it'll spring leaks, etc..if allowed to drop down to a low temp.

Any truth to that?
No truth to that. One of many "old wife" tales widely circulated.

Before DH turning off 70 year old boiler every summer, shuts off water feed valve. When cooled off pressure drops to 0 PSI.

In fall turn on boiler and when reaches set temperature turn on feed valve.

That reduces startup issues.
 
  #15  
Old 06-05-21, 01:38 PM
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G,
Regarding your question about shutting down the boiler causing leaking, if it does happen it is most likely from a weak rubber gasket like the one on your plate where your aquastat is but as a whole nothing will happen.

The boilers today come with just a high limit control unless you have a tankless and are called COLD START boilers which means they only run on demand for heat or hot water if you have an Indirect. If they are just used for heat and you have a stand alone hot water tank which runs independent of your boiler then your boiler automatically shuts down all summer or until you turn up your stat so I would not worry about shutting off the LO LIMIT, especially when your boiler is going to run during the summer at times when you call for hot water so your boiler will most likely always have some temp in it but will not run needlessly.

This is just my thoughts and hope it helps a little but do what makes you comfortable and gives you piece of mind, but .6 gal a day is about 18 gal a month x what a gal of oil cost. Seems like a steep price to pay for rumors.

What you could try is eliminating the LL for a month and see if your gasket leaks. If it does turn it back on and the heat will epand the gasket to stop the leak and run your boiler accordingly.
 
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Old 06-05-21, 06:05 PM
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Will try it out. thanks!
 
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Old 06-08-21, 10:15 AM
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So a slight hiccup with bringing the LO setting to 120. The aquastat is also set at 120.

The boiler temp drops to 120 and once the hot water cools, the circulator kicks in and start pumping water into the hot water tank but the boiler doesn't kick in. Soo..the circulator stays on for a long time just maintaining sub ~120 temp without turning the boileron. I image the boiler will eventually turn on once temp drops low enough but it'll take quite a while.

Upping the LO temp to 140 turns the boiler on and eventually heats the DHW tank.

How would this work with LO being cranked down to its lowest setting?
 
  #18  
Old 06-08-21, 11:32 AM
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G,
Your indirect should be on a zone of its own as the other zones are and operate off the high limit which means on a call for heat or in your case hot water the pump and burner start until the stat or tank aquastat is satisfied.

I noticed on the pic of your tank aquastat what looks like line voltate wiring (120V) which makes me wonder what it is wired too. The aquastat should be 24V, same as your stat wires are. You are controlling your zones with pumps which means you need relays for each pump or something like a Taco control panel.

How is you indirect wired. Could you post pics of your wiring and controls. With your boiler aquastat at 120 what happens when you have a call for heat. Does your burner come on or does it act like the indirect.

My guess is that when they wired your indirect they wired your tank aquastat in a series circuit with the pump and not with your boiler aquastat so the burner is just working off the LO limit as if you had a tankless coil and not using the benefits of an indirect hot water heater.
 
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Old 06-08-21, 06:55 PM
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I noticed on the pic of your tank aquastat what looks like line voltate wiring (120V) which makes me wonder what it is wired too. The aquastat should be 24V, same as your stat wires are. You are controlling your zones with pumps which means you need relays for each pump or something like a Taco control panel.
I believe you're right. The only two wires going to the aquastat is the 110v line which then runs into the main boiler on/off distribution box. As soon as aquastat calls for heat, the circulator starts running and the boiler is triggered by the LO side min temp, which i guess needs to remain at around 140 at this point.

What's the process of setting up a 24v setup, similar to a regular thermostat heat call? Looked at some videos, do I need to get ZR connection involved?


 
  #20  
Old 06-09-21, 03:40 PM
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G,
What is the model number or your boiler aquastat. This is in cas you want to diable the LO LIMIT. Next you have a green Taco box on the side of your boiler. I'm guessing that is a relay and you may need another for the HWH. Can you remove the cover to expose the wires and what goes to it.

What pump goes to C1 & C2 on your boiler control. I sent you a sight in my last post for a Taco SR504-1 relay. If you click on that and follow the wiring instructions you will get an idea of what you need to do. Follow the cold start diagram for no tankless or the alternative if you are leaving your LL hooked up.

Either way you must remove the line voltage wiring from the tank stat and make that 24V going to a relay. The rest depends on what that other green relay is for and what is connected to it. Once you send more info we can proceed to wire it right.
 
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Old 06-09-21, 07:48 PM
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The hot water quastat is Honeywell L4080B 1352
The green Taco box has an additional 24v wire for the attic thermostat that's no longer used (left most Taco Circulator).

C1 and C2 are connected to the house heating loop, there's no tankless coil in the boiler, hot water is strictly coming from the storage tank.

 
  #22  
Old 06-10-21, 12:33 PM
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G,
First, we must get our terminology straight. The aquastat on your tank we will call the 4080 and the boiler aquastat I believe is an 8124? which is the one I wanted the number too but looking more at the pics I believe if you remove the BLUE WIRE you will diable the LO LIMIT on the control and make it a cold start boiler running only on demand for heat or hot water and not maintaining boiler temp when not needed.

Now, going from there you must decide if you want to leave the boiler a warm start as is meaning you want to keep your LO LIMIT in operation or if you want to eliminate your LO LIMIT feature. This choice will depend on how you wire your HWT.

The next question is, is that Taco relay (green box) working and just disconnected. If it is working you can remove all the current wiring going to it and use it for your HWT wiring. If you keep the LO LIMIT you will use your ZC & ZR terminals from your 8124. If eliminating the LL you will need another relay also and wire for COLD START..

The reason for this is if you use your LL the ZC & ZR will activate the boiler and HWT pump. If COLD START then TT will activate the boiler through the relays.

If you look at the Taco SR501-4 relay on the sight I sent you and go to the wiring or install instructions it will show you the schematic. The first one is CS, and the Alternative Wiring is the WS or if you have a tankless which although you do not, that 8124 is made for, so that is the wiring you would follow.

If you wanted to start fresh you could get a new 2 or 3 TACO CONTROL PANEL and have a PRIORITY SETTING for your HWT in the winter.so you hot water would always take priority over your heat in case they both called at the same time ane the boiler had a hard time keeping up. It would shut the heat pump off until the HOT WATER TANK was satisfied so you don't all of a sudden find yourself taking a cold shower because the heat came on.

If you have any electrical experience and can follow a schematic it is a fairly simple DIY project.

One more question I have is how is your HWT pump powered and what turns it on & off and also do you have FLOCHECKS on each zone to stop the water from going only to the zone that is calling or do you get some heat through the house when the HWT or LL calls.
 
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Old 06-10-21, 01:29 PM
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Thanks Spott,
I pulled up the SR504 diagram for cold start - while i can do basic electrical (outlets, switches), relays and varying voltage devices are new to me.

As far as how the HW pump is powered, the HW stat is wired directly through the red on/off switch and when temp drop below min setting, it automatically turns on the HW circulator. The LO limit eventually trips the boiler till it hits max, circulator stays running until temp limit is reach in HW tank.

Both Taco Grundfos have backflow checks so house loop doesn't heat up - though when the HW circulator was running continuously (before HW stat replacement), about 3 feet of house loop got hot since the HW loop kept running.

I have to ponder the new set up a bit:
1. replace 4(NO) and N wires with wiring for the HW circulator instead of those for unused zone 3
2. Thermostat pins on top will wire to the HW stat, R&W TT?
3. 6(NO) and 5(COM) terminal will be twisted together with house thermostat wiring? i'm not clear where this runs to?

Sorry - first time exploring boiler wiring beyond simple component replacement.
 

Last edited by GeneBerg; 06-10-21 at 02:05 PM.
  #24  
Old 06-10-21, 06:12 PM
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G,
No problem. If you decide to go cold start you will need another relay like the one you are not using if that works. In short you will need 2 relays. One for each pump. Each of your stat wires are going to go to the TT on the relays and then 5 & N/O will go to the TT on the boiler control.

You are going to remove the pump wire from C1 & C2 on the boiler control and they will go on 4 N/O & 2 and the same with the HWT pump on the other relay. You can mount the 2 relays side by side and bring in 120V from the boiler switch box as the one is now to H & N. Leave the jumper between H & 3.

The reason you must remove the pump from the C1 & C2 terminals on the boiler control is with the cold start application is because the 2 individual stat wires from the relays are going to go to TT and if you leave the pump as is now every time the HWT stat calls from TTthe heat pump will also start so they must be seperate.

If you wire both zones to the 2 relays as shown that will work. If you do the cold start application you will disable your LL by removing the BLUE WIRE between the BLACK & WHITE wires by the differential wheel.

If you decide to leave the LL the wiring will be diierent but the 2 relays will be the same.

Any questions I'll be here.
 
 

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