Hot water isn't hot enough


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Old 11-21-09, 07:28 AM
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Hot water isn't hot enough

I have a Dunkirk Empire II boiler, oil fired with a Beckett AFG burner. The water limit is set on 200 high and 170 low. I can use the hot water without mixing with cold and put my hand right under it, it's not hot enough. What could be wrong?
 
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Old 11-21-09, 08:17 AM
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What is wrong is that the internal 'tankless' coils are the absolute worst way to make domestic hot water.

Your settings are very high for starters. With your LOW setting at 170, your skin should peel off your hands in about a half second.

But, you probably have a 'TEMPERING' or 'MIXING' valve on the boiler. (MA is pretty strict about this in their codes).

My guess is that mixing valve is pooched.

The other possibility is that the coil inside your boiler is 'limed up' and needs to be cleaned or replaced.

Do you have something that looks like this installed on the water lines at your boiler?:


image courtesy plumbinghelp.ca

In any case, you should turn the 200 down to 180, the LOW setting no closer than 20 below the HIGH setting, and the DIFF at 20. If you try to compensate for little hot water by turning up those dials, you're gonna spend a FORTUNE trying.

If you want to spend money, rather than trying to get the boiler to heat the water with that lousy coil, put the money into installing an INDIRECT WATER HEATER and be done with it.
 
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Old 11-21-09, 11:14 AM
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Hi,

Thanks for the response. It all makes sense, including the indirect issue. I do have a mixer valve, what should it be set to, I believe it is at max.

Thanks,
Doug
 
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Old 11-21-09, 02:31 PM
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Doug, the problem could be both or either the mixing valve, and/or the coil clogged up. Normally, the mixing valve is set up so as to have 120į water at the hot taps. There's minimum chance of scalding with that temp.

Is your mixing valve the type shown? That one is 'thermostatic' and it automatically adjusts itself for the correct outlet temp. If you have this type it's hard to tell where the problem lies...

There are others that are not thermostatic, they are just 'passive' mixers... they look like this:


image courtesy plumbinghelp.ca

If you have this type, and it's at max, then your coil is probably limed up.
 
 

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