Baxi Luna 380

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  #1  
Old 01-30-13, 10:15 PM
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Baxi Luna 380

Just bought a new home read some threads on the Baxi Luna on demand water heating/hot water systems. They are supposedly 98% efficient and save a fuel. I live in upstate New York and have a 2100 square foot home. My system runs on propane and I am paying 2.39 per gallon or pound not sure how its measured, and have been going through 180 gallons a month costing about $400 a month. I was wondering if I should add a standby hot water tank for hot water purposes because it seems to take quite a while to heat the water upstairs and I wonder if that causes the system to over work and therefore burn more fuel! Any thoughts please let me know.
 
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Old 01-31-13, 04:23 AM
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is it doing any heating work also ?
 
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Old 01-31-13, 04:43 PM
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You are only going to get that kind of efficiency if your unit is condensing. If you have radiant heat,cast iron radiators or cast iron baseboard that is good, these type of units LOVE cooler return water temperatures. If you have fin tube baseboard you won't be nearly as efficient. Those boilers must be set up properly with a combustion analyzer and need to need to be run at specific gas pressures. Hopefully your installer was knowledgeable in these units but seeing how much gas you are using I doubt it.
 
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Old 01-31-13, 04:58 PM
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ok, doing the math,
180 gallons * 91,500 btu/gallon
16,470,000 btu.
16,470,000 / 30 days... 549,000 BTU per day.

Thats not a lot of heat really at all.
2100 sqft x 20 btu /sqft = 42,000 btu /hr.
That has the boiler running for 13 hours a day.
20 BTU / sqft is a low number, this would represent a house with good insulation and low infiltration.

Unfortunately, that seems to be the cost of heating with propane.

Unless I am off somewhere in my numbers.
 
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Old 01-31-13, 04:58 PM
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Baxi

As far as it taking a long time to get hot water to your 2nd floor, it has to do with the distance your bathroom is from the unit, you will not get hot water any faster with a storage tank and you will be using even more fuel to keep a tank full of water hot 24/7. The purpose of a combination unit is that it will only make hot water as you need it.
 
  #6  
Old 01-31-13, 05:14 PM
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we have had to deal with issues like these on some jobs.
We installed a 5 gallon electric tank close to the furthest highest usage hot water tap.
The tank will get feed by the main hot water system, and the electric element ,while set low, will keep the tank warm and ready to go.
The plus side is you don't get the cold water sandwich common with tankless.

I think I would do anything but heat with oil or propane... such a high priced fuel.
Yet a burn propane in my truck and it's cheap cheap... I don't understand why it costs so much to heat with propane. I can see oil, its basically diesel and the trucks try there hardest to burn thru all that.
 
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Old 01-31-13, 06:32 PM
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"I think I would do anything but heat with oil or propane... such a high priced fuel." Thanks a lot TO,I have no choice but to use oil,and I am a gas guy,lol. There is gas a few hundred north up the street and a few hundred feet south down the street but nothing close enough for National Grid not to charge me a fortune to bring it into my property.
 
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Old 02-02-13, 07:27 AM
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According to my manual, you need 27.4 mbar or11.0 ft/wc to operate this unit, and with a combustion analyzer your CO2 %'s should be,10% @ max heat,and 9.8 % @ min heat..you need someone qualified and with the proper
equipment to perform the tests and make adjustments as needed.
 
  #9  
Old 08-26-13, 05:27 PM
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Unhappy Baxi luna 380 hot water flow problem

Hi,

I have a baxi luna 380 combi gas boiler that provides heat and on-demand domestic hot water. I have the following problems with the hot water flow:

1)If the water flow out of a hot water faucet is slow then the boiler fails to turn on the burner and no hot water comes. I recently changed one of my faucets and for some reason the flow is lower than the old one and I do not get any hot water.


2)On the second floor bathroom shower the hot water is mildly warm and the flow switches between cold and warm - the hot water is not steady.


Please help?
 
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Old 08-26-13, 05:58 PM
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Sounds like your temperature sensor for domestic water may be shot, or perhaps the flat plate heat exchanger needs to be flushed...both of those are possibilities with the symptoms you describe.
 
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