DHW advice needed

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cricco

New Member
Mar 25, 2008
49
Western, Ma
I am trying to find a solution for a problem I have with my newmac wood/oil boiler. I have an indirect DHW heater (85 gallon weil Mcclain). I have been using oil to heat my DHW during the summer months. This causes the boiler to run a lot in order to keep it at temp to heat the indirect water heater. The boiler also has a hot water coil, which is not in use. To save oil, we have been shutting the boiler off manually and only turning it on in the morning and evening. The water seems to stay hot most of the day without the boiler running. The boiler does NOT stay hot all day. I have thought about installing a seperate DHW heater for summer, but it seems a bit expensive and I would like to find a cheaper solution. Does anyone have any ideas on how I could run this system more efficiently? I don't need heat in the summer, just hot water.
 
You might think of getting a tankless hot water heater..... Yah, you'll be using propane all winter then to heat hot water, but they are hands-down the most efficient way to heat hot water if going with gas.........

Plus, nobody says you can't bypass the tankless and go back to your old setup in winter..... If you plumb it up with that in mind..
 
While I don't have my wood boiler yet I'm considering the same delima...how to heat my dhw in the off season. Currently my oil boiler does it but I'm sure I'm wasting a lot of $$ this way based on how many times the oil boiler kicks on for just the 2 of us. Had thought about propane tankless but we don't want a tank near the house. Almost went with an electric tankless but have read and heard too many negative comments about them plus we only have 200 amp service and may have had to upgrade that for electric. Have decided on an efficient as possible old fashion electric tank...plus a sidearm at a future date. Going to install a timer so it only heats during the normal usage hours and it will be turned off when we go away for the weekend(not often enough!) and during the heating season.

We may look at an indirect tank once the wood boiler is in place if we don't go with "storage" but was told to not bother with an indirect tank if relying at all on oil to heat it for your vaery same reason.

Your oil/wood combo boiler is still on my possible purchase list and would like to hear from you (pm?) regarding pros/cons of it through the heating season.
 
muncybob said:
While I don't have my wood boiler yet I'm considering the same delima...how to heat my dhw in the off season. Currently my oil boiler does it but I'm sure I'm wasting a lot of $$ this way based on how many times the oil boiler kicks on for just the 2 of us. Had thought about propane tankless but we don't want a tank near the house. Almost went with an electric tankless but have read and heard too many negative comments about them plus we only have 200 amp service and may have had to upgrade that for electric. Have decided on an efficient as possible old fashion electric tank...plus a sidearm at a future date. Going to install a timer so it only heats during the normal usage hours and it will be turned off when we go away for the weekend(not often enough!) and during the heating season.

We may look at an indirect tank once the wood boiler is in place if we don't go with "storage" but was told to not bother with an indirect tank if relying at all on oil to heat it for your vaery same reason.

Your oil/wood combo boiler is still on my possible purchase list and would like to hear from you (pm?) regarding pros/cons of it through the heating season.

You might want to read this:http://www.leaningpinesoftware.com/hot_water_heater_vacation.shtml

This guy does a pretty good analysis of the difference between turning off the water heater and not.
His conclusion was that the savings would be negligible.

A well insulated water heater should only loose about 3* over 24 hrs.
 
how much hw do you use?
Off "heating" season you might use an electric tank, depending on your KW/hr. cost, and dhw usage. Electric costs vary widely, I've seen 4 cents/ kwh in Minnesota, and hear 12-15 cents in parts of New England.

In many areas solar can provide all or most of the summer dhw load. A solar tank with a top only electric element would be another option. Valve it so in the winter month the solar tank feeds into the Weil as a pre-heat. In the summer tank the solar feeds directly to the house. Electric backup element with a timer to keep it off while you are away at work, possibly.

Given a choice I spend the money on solar before an instant type DHW heater. 30% federal tax credit plus any state rebate makes solar fairly attractive.

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