Need a DHW solution for low basement.

DavidG

I am fed up with running my oil fired boiler all summer long just to heat our hot water. It is terribly inefficient. The problem is that the basement is very low, around 5'. And there is no place upstairs to put a taller unit. I have tied.



I could go with just a ordinary electric heater, in fact there is an old one there I can cut over to if I replace it. But I would much rather go for a more efficient heat pump heater. And I get the advantages of dehumidification which will also save me money.



Anyone have comments to make on the retro-fit units? I have a Buderus hotwater tank now. I think I read somewhere that one of the reto-fits requires you change a very expensive sacrificial rod ever year.



DavidG

Charlie from wmass

David if you have a buderus tank now

and your system is in proper running order you are producing hot water about as cheap as you can with out investing into solar water heating. running the boiler also keeps corrosion down and keeps the boiler in running order for next year. Make sure it is properly cleaned and tuned each year. yes the tank has an anode rod. There is a service procedure for it to make sure it is still working ( not eaten away). You can find this by looking at Buderus' web site and looking up your model number.

Robert_25

?

David, what makes you think your current system is "terribly inefficient"?

DavidG

Good advice

I do have it cleaned annually but even so I have my doubts how efficient it it heating itself up just for a little hot water. But I agree, keeping it running during the very humid months does have some merit. The anode story I was referring to I think was related to the AirGenerate heat pump. Someone said that they were insisting that you replace a $300 anode they sell every year. That is not what they recommend on their web site now. But I will take your advice and check on the Buderus site to check mine.



See my next response on why I think it is inefficient.

DavidG

My calucaltions.

Robert asked why I thought it was inefficient.



Just so you know, I keep a lot of records, running time, oil consumption, degree days and such. But it is always helpful to have others check my numbers to keep me honest.



The boiler runs approximately 25 hours a month during the summer when no heat is needed. Up here in Maine that is one month. It burns 1 gph which translates to 2.5 mbtu per month. Currently oil is pushing $4 so that is $100 a month, just for the hot water.



There are just two of us here, and we have efficient appliances and take short showers. I estimate we could heat the same hot water with 200 kWh per month. Looking at new efficient hot water heaters they say about 400 kWh but I think that is for a family of 4.  At $0.16 a kWh that means $32 to $64 a month. And in the winter the boiler could concentrate on heating up the house in the morning, not both hot water and the house.



So that would be a savings of $36 to $58 a month. Not a small amount.



And the dehumidifier would run less, if at all. Which reminds me, I need to put the CurrentCost meter on it now that it is humid and get a good reading on how much it is costing a month.



Just found last year's data on the dehumidifier, it uses aprox. 200 kwh per month, or $32 a month.

James Day_2

Boiler?

David,

What boiler is feeding your tank?  What is the tank temperature set to.  Pictures would help. 

DavidG

Buderus

Its a Buderus 215 (which is a bit oversized for the house), tank temperature is set at 125. 

icesailor

Solutions:

I think you have over thought this situation.

I think you are one who is willing to spend $5.00 to save a dime.

You have a better system than I have and I don't spend what you do. Something is wrong or you are seeing things that aren't really there.

My wife and I can take showers one after another or at the same time without running out of hot water. If she ran out of hot water when in the shower, or any of my customers run out of hot water while in the shower, life as I (we) know it isn't worth living. No amount of cheapness is worth it.

I did a really expensive bathroom for a customer. Custom tiled shower with a big shower head and recirculated hot water so she didn't need to wait for hot water. She told me after a month how she hated her shower that she couldn't get the soap out of her hair. I told her that that was the first I heard about it and I would fix that instantly. I removed the flow restrictor from the $900.00 shower head and she couldn't be happier. She has clean, soap-less hair now. 

Be careful what you wish for. You might get it and be unhappy with the results. 

Larry Weingarten

curious

Hello David:  I'm curious to know if you have some sort of recirculation on your domestic hot water piping.  Running close to an hour daily sounds like far more heat is going into the system than you're taking out.



Yours,  Larry

DavidG

Maybe, maybe not

I do tend to think about things a lot, but then, that is how new discoveries are made. I think I am looking at spending maybe $800 for a retro fit DHW heat pump and saving probably $800-$1000 a year. That is a very short payback time. 

DavidG

No reciruclator

And there does not seem to be any theromosiphoning either. So yes, something is out of whack. I've been blaming it on the time it takes to get the boiler up to a high enough temperature to heat the water. At least in the winter there is not that cost.

Larry Weingarten

Air Tap heat pump...

... is a retrofit unit (good for low ceilings) and it does put a large copper coil in your tank.  So, if the tank is glass lined, you'll need a good anode.  I don't know if it can be made to fit, but there is a powered anode that can be used rather than a sacrificial rod.  The engineers at Air Tap  are experimenting with a refillable anode also.  I have a friend who managed to fit Air Tap units to Marathon heaters, which need no anode.  Choices!



Yours,  Larry