Weil-Mclain CGa-4 and Aqua-Plus 45 Indirect Water heater

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Old 07-04-20, 12:20 PM
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Weil-Mclain CGa-4 and Aqua-Plus 45 Indirect Water heater

We had a Weil-Mclain CGa-4 with the Aqua-Plus 45 indirect water heater installed which ran great throughout the winter. Everything worked as expected with the indirect on a priority zone for DHW so we always had enough hot water and the boiler ran longer and cycled less often than with the prior CGa-5 with our copper-finned baseboard.

The boiler temperature was set to 180 degrees for our copper-finned baseboard heat and we set the indirect set at 140 with a mixing valve based on recommendations to avoid any potential for Legionella disease.

Now that it is summer though I am curious if the boiler setting should still remain at 180 or does it make sense to reduce it to say 160? The WM has a 20 degree differential as I understand it so if it were set to 160 the low point would be 140 which would be the same as the indirect. Or does it just make sense to leave it as is since talking pennies and better for boiler to be set at 180 all year round?

Thanks in advance for any perspectives.
 
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Old 07-04-20, 03:38 PM
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Try it

Well, you won't save any significant fuel - a little, maybe. But, I would experiment with it. Good way to spend some time while you are shielding from the virus
 
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Old 07-05-20, 12:35 PM
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D,
D o you know you are dealing with 2 different temps controls or actually 3 counting your mixing valve..

Your boiler water is controlled by your boiler aquastat, your Indirect is controlled by your tank aquastat and then your mixing valve is set to what you want coming out of your faucet.

If you turn down your boiler temp you will still get 140 at the the tank but it will take you longer and depending what your mixing valve is set at it may have trouble keeping up.

If you turn down your Indirect but leave your boiler at 180, your boiler will not run as long but you won't have as much reserve in the tank to keep up with the faucet demand and the boiler will run more.

If you leave everything where it is because you have been happy it may cost you maybe another .25 cents if any at all but the wife will be happy which will make you happy and save you more than a quarter on the aspirin you won't be needing.

It's tough to put a price on peace and harmony, especially with the present situation.

Hope this helps a little. Personal opinion, leave as is, stay safe.
 
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Old 07-05-20, 03:00 PM
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Very sage advice. Thanks as that is where I'm at.
 
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Old 07-05-20, 05:07 PM
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There is an Economy Adjust setting on the Weil-Mclain boiler which delays the firing of the boiler to first see if the call for heat can be satisfied by existing boiler water temperature. It is set to Min but the manual indicates the preferred setting is Max. Not sure if this adds any value changing this?

Also, I timed the cycle time the last few times the indirect called for heat with the boiler set at 180 and it only fired until about 160 or so before shutting off and then the heat soak brought the boiler up to 180 on the dial.

Since the boiler is only being used for the indirect water heater this time of year wouldn't a lower setting say 170 or even 160 (which is 20 degrees higher than the 140 setting on the indirect. Mixing valve set at 120) allow the boiler to run a longer run time which may be more efficient and better than short cycling the boiler?

Thoughts please?
 
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Old 07-06-20, 12:32 PM
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D,
If you go to the sight below and click on install instructions and then go to page 6B and 8 it will explain what these controls do and you can play with them until you are comfortable. It is easier than trying to explain it and you can make up your own mind what works for you.

https://www.supplyhouse.com/Weil-Mcl...nition-Nat-Gas
 
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Old 07-06-20, 01:39 PM
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Thanks Spott, saw and reviewed this info earlier on the "Economy Adjust" setting and was confused why if "Max" is preferred then why our boiler was set at "Min". I have a txt out to the installer but was curious if any other perspectives from the professionals on the site.
 
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Old 07-06-20, 08:59 PM
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The difference is with the knob on max, say the boiler was off on high limit when a call for heat or hot water came the pump would circulate the hot water from the boiler until the sensor sensed the water was too cool to do any good and the burner would come on and reheat the boiler water, so max would keep the boiler off longer as long as you had heated water in the boiler and was senser was satisfied.

On minimum on a call for heat or hot water the boiler will start imediately with the pump no matter what the boiler temp was, so max can possibly save you some money depending how many zones you have and how long they are.

As far as you playing with the temp controls as long as you get sufficient heat and hot water you can turn it to whatever does the job for you. There is no real rule because evertone is different.

I will say this. Indirects just like baseboard needs 180 deg water feeding it to get the rated performance the company's claim. If you need less hot water than the tanks rating you can run your boiler lower. All ratings be it baseboard, tankless or Indirect hot water heaters are all figured with 180 deg supply water to them.

 
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Old 07-07-20, 10:17 AM
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Thanks again Spott for your input. Makes complete sense. Much appreciated.
 
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