Radiant Heating / Hot water question

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Old 01-02-14, 04:18 PM
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Radiant Heating / Hot water question

I have an oil fired Buderus Logano G115 with a Buderus Logalux LT. It is a closed loop radiant heating system. The problem is the hot water side, I cannot seem to adjust the temperature down below 170 at the tap. I have adjusted the Honeywell Sparcomix valve all the way to the cold side with no noticeable changes. My boiler pressure is 15psi and my return water temp is at 80 degrees. I am at a loss, but know that this water is way to hot.
 
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Old 01-03-14, 01:02 AM
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The Sparcomix is defective. Maybe you can rebuild it or maybe it needs to be completely replaced. Check first to see if the cold water supply to the Sparcomix is turned on.
 
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Old 01-03-14, 02:13 AM
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That is what I was thinking, as I am new to these radiant systems. I am confused as to the cold water supply, on this closed loop system it seems to be the return water from the heating loop is being used for the "cold" side of the sparcomax. Is this the norm on these systems?
 
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Old 01-03-14, 05:53 AM
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Hi James, I want to be sure that we're all on the same page here...

I cannot seem to adjust the temperature down below 170 at the tap.
I think you are talking about your DOMESTIC hot water tap here?

If so, I need to ask you what the SOURCE of your domestic hot water is. Does you DOMESTIC hot water come from the boiler itself, INDIRECTLY via boiler pipes connected to a water heater?

Or do you have a completely separate stand-alone water heater with NO CONNECTION to the boiler?

It is a closed loop radiant heating system
"Radiant" can have slightly different meanings... the term is somewhat ambiguous.

Are you describing a system where the heat tubing is under the floors?

Or do you mean that you have hot water baseboards or radiators in the home?

my return water temp is at 80 degrees.
Is this a temperature you are reading on a gauge on the boiler piping?

I am confused as to the cold water supply, on this closed loop system it seems to be the return water from the heating loop is being used for the "cold" side of the sparcomax. Is this the norm on these systems?
There is no 'norm' for a heating system really... all are different.

I think there is confusion in terms and understanding of function of the controls.

more...
 
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Old 01-03-14, 06:01 AM
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You need to take pictures of your system all around to clear the confusion...

Here is what I suspect you have, please verify the details:

IN-FLOOR RADIANT HEATING, where tubing is run on the underside of wooden floors, or embedded in a concrete slab.

AN INDIRECT WATER HEATER, where you will have FOUR PIPES in and out of the hot water storage tank. TWO of these pipes will travel back and forth between the tank and the boiler piping. The OTHER TWO pipes will be your COLD domestic supply into the tank, and the other will be the HOT supply out of the tank to the hot water taps in the home.

Is there only one SparcoMix valve on your system? Do the pipes on this valve go to and from the heating tubing in the floors? Is there a PUMP on the "MIXED" outlet of the SparcoMix valve?

If so, adjust it BACK to where you found it. This mixing valve is NOT for your domestic hot water and adjusting it will have no effect on the domestic water temperature. If you leave it where it is, very soon you will find the home cooling off and be unable to heat it back up.

In GENERAL, the MIXED hot water coming OUT of a valve that feeds in-floor radiant tubing should be in the neighborhood of 120F and in some cases LESS... but rarely more.

more...
 
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Old 01-03-14, 06:07 AM
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Many of these questions can be answered with clear, well lit pictures of the system... but until then, I will continue.

If, as I suspect, you have an INDIRECT WATER HEATER the temperature of the tap water will be controlled by a thermostat installed on the water heater itself, probably underneath an access cover of some type.

Don't remove any covers yet! Because if I am WRONG in my suspicion, you MAY have an electric water heater and removing covers without turning off the power can put you in harm's way... there is DANGEROUS HIGH VOLTAGE under the access covers of electric water heaters! Don't kill yourself!

Lastly, some HISTORY of the system. Have you lived with this system for some time, and is this a NEW PROBLEM that has only just occurred recently? OR is this a NEW TO YOU system and has always operated this way to your knowledge?
 
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Old 01-05-14, 10:44 AM
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Sorry for the delay. The boiler supplies my hot water as well as my radiant in-floor heating system. The problem is my tap water is coming out 170 degrees, and I cannot get it any colder. I do not have a separate hot water heater, or I would just turn down the thermostat Hope these pictures clear this up
 
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Old 01-05-14, 11:22 AM
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You DO have an 'indirect water heater', it's the one in this picture. The boiler is on top the water heater on the bottom.

That Honeywell box on the front of the water heater, what is it set to?

THAT is the domestic water temperature setting control.

You really need to get this system tended to. That leak from the fitting on the bottom of the boiler is only going to get worse until at some point it may not be able to be repaired.

Why is the paint all peeled off the boiler? Makes me think something else is going on as well.

Can you stand back with the camera some and get a WELL LIGHTED picture of the whole system please?
 
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Old 01-05-14, 11:27 AM
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This valve is NOT for your domestic hot water, it is for a RADIANT HEATING subsystem.

You need to set that back to where it was... this should supply about 120F water to the radiant floors. If one of those thermostat gauges is on the outlet of that valve, adjust the valve for 120 after the system is up to temperature but still calling for heat.
 
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Old 01-05-14, 01:39 PM
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The paint is not peeled, the back plate is galvanized steel. We just bought the house and I have noticed the leak. I want to fix it just don't want to tear down the connections in January in VT. Plus ideally I am going to switch to a pellet boiler before next season.
 
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Old 01-05-14, 01:47 PM
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I want to fix it just don't want to tear down the connections in January in VT.
Can't blame ya for that!

That Honeywell box on the front of the water heater, what is it set to?
Have you had a chance to look at the setting yet? I'm curious to see if someone really turned that up to 170 or if the control is bad.
 
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Old 01-05-14, 02:45 PM
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No the switch is set to 100, guess I may have a bad switch. I will check it with my DMM and if so get a new one in the morning.
 
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Old 01-05-14, 04:24 PM
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Check the wiring too James. Maybe a short.

100 is too low. When fixed, use 120 - 130 max.

It's possible that it's not piped properly too. Might be getting unintended flow when not being called.

How are the two pipes on the right and left connected into the boiler piping?
 
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