Aquastat replacement

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Old 10-19-15, 07:18 PM
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Aquastat replacement

I have a gas hot water baseboard heating system with two taco zone valves. Its about 30 years old. The burner cycles on and off too frequently, about every 6 minutes. I want to replace the white rodgers aquastat and a direct replacement seems to be honeywell L8148J1009. However is has a fixed 8 degree differential and I am concerned that it too will cycle the burner on and off too frequently, as I am not sure the existing aquastat is defective. The only other aquastat I can find is honeywell L8148E1265 which has a 15 degree differential. This one seems better but the wiring is not as simple as the J1009. For instance the E1265 does not have a TP terminal. I dont know how to connect the thermostat (zone) wires. The burner is 24V. Please tell me if I am headed in the right direction and any help with the wiring will be GREATLY appreciated. The taco valves are three wire.
 
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Old 10-20-15, 06:45 AM
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Please tell me if I am headed in the right direction
If you want to throw parts $$$ at a perceived problem, then sure...

Let's talk about the 'problem' though before you do that.

The burner cycles on and off too frequently, about every 6 minutes.
While a wider differential will help to mitigate this to some extent, it's MUCH more likely that the problem is an oversized boiler.

Widening the diff will STILL CYCLE albeit at a slower rate. Make the diff too wide and you can sometimes 'feel' temperature swings in the building... but that's not too likely with a diff of 20F or so.

How many square feet is the home?

How many BTUH is the boiler?
 
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Old 10-20-15, 08:42 AM
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aquastat replacement

OK the house was built in 1983 and is 1860 square feet not including unheated basement and garage. The boiler says input BTU per hour 150 000, heating capacity 118000 BTU per hour. I just thought that the burner was igniting too frequently, 10-12 times per hour when thermostat is calling for heat was abnormal. I do appreciate your feedback .
 
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Old 10-20-15, 09:02 AM
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I just thought that the burner was igniting too frequently
It might be, but it is probably not the fault of the control.

The boiler is definitely oversized for the home, maybe as much as 2X over. The result of that will mean shorter burn times because you can't take the heat out as fast as it's being produced. If the thermostat is still calling for heat, when the water cools off the burner will fire again and the cycle will repeat until the thermostat is satisfied.

If the boiler were correct sized, the burns would be longer.

Is this a 'new to you' home? Do you have history with this system? Has it always worked this way or has something changed recently?

One thing that you can do if it has not been done recently is to remove the covers from the baseboards and vacuum the dust out and brush the fins. This will increase the rate at which the heat is moved into the home. You will still have short-ish burner cycles, but if you can get the heat into the home more quickly, perhaps less of them.
 
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Old 10-20-15, 09:52 AM
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aquastat replacement

I have cleaned out the fins with compressed air, so they are probably not contributing to the 'problem'. I have lived in the house since 1996 and I cant say if I noticed it back then, but its been doing this for at least a few years. The existing aquastat (I left the cover at my parents house otherwise I would give you the model number) is probably as old as the house and the transformer has a hum to it, not really that loud but you can hear it from a distance, so I thought it was time for replacement. The L8148J1009 has exactly the same terminals so it would be easier to wire. But is only has a 8 degree fixed differential. The L8148E1265 would be harder to figure out without some assistance (15 degree differential). Also, I am just concerned that parts in the boiler will wear out faster due to the frequent cycling. I just dont want the existing aquastat to quit in the middle of the winter or when I am not home. Would you recommend replacing the old aquastat, and if so, which model would you recommend (I am open to other models than I mentioned). Thanks.
 
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Old 10-20-15, 04:46 PM
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aquastat replacement

Well now I am totally confused. I contacted a local supply house and they told me its not the aquastat but the problem is with the taco valves and/or the thermostat. He said the taco's are too power hungry compared to Honeywell valves and are causing the problem. He also mentioned something about the heat anticipator in the thermostats since they are of the programmable kind. I dont understand how this fits in with the cycling issue but maybe you could explain.
 
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Old 10-20-15, 05:11 PM
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Oh boy... a counter guy at a supply house... he didn't understand what you were asking him, and spewed a bunch of crap, sorry.

You think everything is original and it's been working for 30 years and now all of a sudden the zone valves are too power hungry?

Are the zone valves powered by a separate external transformer? Or are they powered from the transformer in the aquastat?

Please tell me the model number of that W-R aquastat.

Look around the Taco valves for a transformer mounted on the wall or ceiling somewhere.

Take pictures if you can, but if they are not well lighted and in focus and large enough for old eyes to see, they will be of little use.
 
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Old 10-20-15, 05:13 PM
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The cycling you are hearing has nothing to do with the humming transformer. Transformers do that as they age. The laminations get loose and vibrate.

I'm not saying that it might not be time for a new aquastat, but I honestly don't think there's anything wrong with your system that a new aquastat will fix.
 
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Old 10-21-15, 09:08 AM
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aquastat replacement

It is a W-R 8J48A. There are no additional transformers. Taco 571-2. There are two zone valves each 0.9 amp. I took some really clear photos but the site would not upload them. I dont know why. Each picture is about 9.62 mb and it looks like a max of 10mb is allowed. Can I send you the pictures by other means? I just dont know what I was doing wrong if anything. Thanks
 
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Old 10-21-15, 09:59 AM
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aquastat repacement

OK different camera. Hope this works I may have to send one picture at a time
 
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Old 10-21-15, 10:33 AM
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http://www.doityourself.com/forum/el...-pictures.html

The board has a limit of 50Kb and 600x600 size per picture. The 10Mb refers to total storage.
My link above describes this. You can host them at photobucket, which is free, and then link them here.
 
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Old 10-21-15, 12:48 PM
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aquastat replacement

 
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Old 10-21-15, 05:19 PM
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Much as I hate to admit it, the counter guy was correct. My apologies to the counter guy. The transformer in your aquastat IS overloaded by running two Taco valves from it.

You would probably be OK if only ONE zone called at a time, but when BOTH zones call at the same time, the transformer is overloaded... the fact that it's lasted this long is testament to the way the built stuff back in the day. A new one would not last this long being overloaded.

It is still only a matter of time before that transformer gives up it's ghost. Or, maybe never. It's a gamble.


BUT, that is NOT the reason that it is cycling so often! Your boiler is still over sized and this is the reason for the cycling...

AND... there may also be another reason that is contributing.

What type of thermostats do you have installed? Do you know if there's an 'anticipator' setting on those thermostats? If it's set wrong it can lead to short cycling issues.



What I would do if this were my system is FIRST do one of two things:

1. Install an external auxiliary transformer to power the zone valves and get that load off the transformer in the aquastat. This would mean running a 120VAC line to a 4" utility box to mount the transformer. Then, rewiring the valves so they run off the new transformer.

2. Install a TACO ZVC zone control panel. It still means running a 120VAC line to the new panel. The needed transformer is installed already in this panel. You would then run the thermostats into the new panel, and wire the zone valves to the panel.

ZVC403-4 - Taco ZVC403-4 - 3 Zone Valve Control Module with Priority

After this was done, that transformer would probably not hum as loudly.

NEXT, you could consider replacing the aquastat, but again, it's not going to help the cycling issue in and of itself. There are several that would work for you.

So, check those thermostats and let me know what they are and we'll go from there.
 
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Old 10-21-15, 05:23 PM
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Old 10-21-15, 07:58 PM
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aquastat replacement

I have two thermostats, both of which are programmable and I dont think they have anticipators in them (one is smarttemp TX500 and other is honeywell magicstat 32. If I bought two honeywell V8043E zone valves would I still have to add transformer(s). I am just trying to figure out which is simpler. The Taco control box seemed a little complicated. I have two sets of wires coming from basement ceiling for each thermostat(one white wire and one red wire). The white wire goes to term 1 on each Taco. Term 2 on each Taco are interconnected by a wire and a white wire from one Taco(see pic) goes to term TV on aquastat. Term 3 on each Taco is interconnected by a wire and a blue wire from one Taco(see pic) goes to term T on aquastat. The red wires are interconnected and go to term Z on aquastat. I know basic electricity and could connect 120 VAC to transformer with no problem. I would need help connecting transformer to zone valves/thermostats. I would really like to understand all of this as I am not working and have the time and always willing to learn. I do
everything myself but this is new to me and would need help with wiring.
 
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Old 10-21-15, 08:27 PM
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I dont think they have anticipators in them
No, probably not. But download the manuals for them and see what settings you do have. Look for one called " CPH " (cycles per hour) and read up on what that does.

If I bought two honeywell V8043E zone valves would I still have to add transformer(s).
Yes... that existing aquastat only has about 0.60 A of capacity to run zone valves and as I recall two of the 8043 are still higher than that. (been a while since I looked at the specs and memory not what it used to be)

And changing the valves out, now you're talking about a plumber coming in... $$$


The Taco control box seemed a little complicated.
It's really not. But I don't know your background or skill set.

Basically all you do is mount the panel, run a 120VAC line to it.

There are terminal strips for each thermostat, and each zone valve. Just hook up the wires.

Then a single pair of wires from the panel to the boiler.

It's actually easier than mounting and wiring the transformer because you don't have to figure which wire is connected to which wire. On the panel, each wire has it's own spot, you put the wires in and tighten the little screw.

I can help you with the wiring when you decide what you want to do with it.

I believe that this drawing is more or less what you have now, terminal names may or may not be the same, but the wiring is functionally the same:

I'm not saying that this is right... it's just the way yours is. SOME aquastats in the past had a big enough transformer to be able to run two zone valves.

 
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Old 10-22-15, 12:41 PM
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aquastat replacement

I went to the supply house and the counter guy showed me a wiring diagram for a separate transformer. Basically one wire from transformer interconnects with the white wire coming from term 2 on Taco valve and the other wire from trans. connects to red wire from thermostat. I just not sure if the red wire still connects to term Z on aquastat. He suggested a honeywell L81482199 aquastat which has a 50 vA transformer built in and a 15 degree differential. So I have those two options, I also have the aquastat you recommended. The problem with the Honeywell is that they recommend the heat anticipator set to 0.2A. But I have no anticipators in my thermostats. The one on second level is set to max swing setting of 5 which means less cycling, although it calls for heat when the hallway temp is only about 2 degrees from set temp. But I dont have problem with that part of cycling, the short cycling I m concerned with is the boiler firing too often which is controlled by aquastat. I do have the ablilty to replace the zone valves myself if it comes to that, since i already replaced the hot water heater previously.
 
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Old 10-23-15, 06:47 AM
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aquastat replacement

Could you explain to me how the current flows in that diagram you posted of the terminals when the thermostat calls for heat. I am trying to figure out if the 1299E aquastat would work. If I cant determine this I am going to buy a transformer and hopefully wire it correctly.
 
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Old 10-23-15, 03:57 PM
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explain to me how the current flows in that diagram
The 24V transformer secondary is wired to the TV and W,Z terminals. One lead of that voltage source goes to the thermostats (which are SWITCHES). The other lead goes to terminal 2 of the zone valves.

When the switch (thermostat) closes to call for heat, it completes the circuit to the motor on the zone valves which is between terminals 1 and 2.

The motor then is energized and opens the valve.

When the valve is open, it trips an ENDSWITCH inside the zone valve.

This endswitch then triggers the boiler to fire.

A 50 VA transformer, if that's what the -1299 aquastat has is enough to run two zone valves.
Just looked at the specs, it is a 50VA transformer and would run three Honeywell valves, and easily two Taco valves.

Don't pay too much for it locally:

Order it from these guys and you'll have it in two days... if you want to go that route.

L8148E1299 - Honeywell L8148E1299 - High Limit Vertical Mount Aquastat Relay, 15F differential w/ 50VA Transformer
 
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Old 10-25-15, 11:50 AM
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aquastat replacement

I am going to order the 1299E from the place you mentioned. Its about $100 less that the local supply house. At least it has a transformer that will power the taco
zone valves and it will be new, not 32 years old. If it helps the burner from short cycling fine, if it doesnt well at least I have a new aquastat. Thank you for your assistance, its greatly appreciated.
 
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Old 10-25-15, 05:04 PM
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It's likely that your old a'stat only has an 8 or 10 degree diff. The 15 diff will help the cycling.

And yes, the transformer in that is more than enough for your needs.

The wiring is the same I think.

Yes, please let us know how it goes!
 
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Old 11-04-15, 07:06 PM
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aquastat replacement

I finally got around to replacing the aquastat today but the probe on the old one seems to be stuck in the immersion well. I did not want to pull too hard for fear of breaking the probe and it being stuck in the well. Is it possible the heat conductive compound ( if any was used in the original install 30 years ago) is preventing the probe from coming out. What should I do maybe pull harder? Do I have to drain the lines or could I just unscrew the old immersion well and screw in the new one( if the probe breaks). I have not used heat for a few days due to the warm weather so the water should not be too hot. What would you recommend?
 
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Old 11-05-15, 09:46 AM
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aquastat replacement

OK, the probe came out of the well easy with a pliers, which I could not find yesterday. The instructions call for the casing to be connected to an earth ground (there is a screw on the bottom of aquastat to attach a wire). Since I have BX cable attached to case is this sufficient? If not can I run a wire from case grounding screw to cold water line.
 
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Old 11-05-15, 11:16 AM
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The BX should be sufficient. It's also mechanically grounded to the boiler itself via the clamp mechanism.
 
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Old 11-10-15, 09:05 AM
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Aquastat replacement

Well I successfully installed the new aquastat. It was easier than I expected, the new probe fit snugly into the old immersion well so no need to drain boiler. However, as you hinted to before, the new aquastat did not help the short cycling of the burner. The old aquastat had a 8 degree fixed differential compared to 15 degree on the new one. The odd thing I noticed is that I dont see a significant difference in temperature on the dial on the boiler from the time the burner shuts off and when it fires again. Maybe the temp gauge on the boiler is not that accurate, but is does seem to work. For instance when the heat is not used for awhile, say 12 hours, the dial indicates about 100 degrees. When the heat is turned on and the boiler heats up the temp dial registers about 170 just before the burner turns off. I have to assume the new aquastat is operating correctly. Anyways, I think it was a good investment and happy that I replaced it.
 
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Old 11-10-15, 09:54 AM
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the new aquastat did not help the short cycling of the burner. The old aquastat had a 8 degree fixed differential compared to 15 degree on the new one.
Right, it will still cycle... but it should stay OFF LONGER, and then when it fires, stay ON LONGER because the water is a few degrees cooler. In other words, the 'duty cycle' will stay the same, but the 'frequency' will change.

The odd thing I noticed is that I dont see a significant difference in temperature on the dial on the boiler from the time the burner shuts off and when it fires again. Maybe the temp gauge on the boiler is not that accurate
Could be the gauge... sure... but also, the position of the gauge in the boiler versus the position of the immersion well with the aquastat... could well be subject to different temperatures.
 
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