Should I buy a water heater for my McClain Gold WTGO-4?

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Old 04-11-08, 02:04 PM
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Should I buy a water heater for my McClain Gold WTGO-4?

I have a Weil McClain Gold WTG0-4 boiler and Iím a little concerned heading into the summer using it to heat my hot water. I bought this house last year and was told that this unit didnít need a separate hot water heater, that it heats the water on demand. Well when I filled up my oil tank last fall I calculated that I used about 30 gallons a month just to heat the hot water in the summer. 30 gallons a month this summer is going to cost me upwards of $100. That seems more than it should be. Would it be less expensive just to buy a separate water heater? I thought that maybe the cost of heating the water in the summer would even out in the winter when I effectively wouldnít have to pay for hot water because the boiler was running more often but I have my suspicions that the boiler heats the hot water we use for washing independently from the hot water that heats the house. Is that true? If it is, then what exactly is the benefit of not having a separate water heater outside on a lower risk of flooding my basement? Also can someone tell if I should change my aquastat settings for the spring and summer? Right now the low is at 170 and the high is at 190 with a differential of 10.
 
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Old 04-11-08, 03:40 PM
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What you have there is a 'tankless coil' water heater installed in your boiler. The boiler needs to stay warm all the time in order to heat your domestic. This is probably the most inefficient way of producing DHW.

What are your alternatives ?

You could install an electric water heater. Depending on the size of the heater and your family, and the cost of your electricity, this might cost say ballpark $35-50 / month. Installation ? I dunno, depends on where you live sorta... here in the N.E. I think it's safe to say it might cost like $800 for installation, kinda high because it's not just a 'swap out' job. The plumber will need to do some piping...

You could go with an 'indirect heater'. Still runs off your boiler, but the boiler will only fire up when needed to keep the storage tank of domestic hot. The boiler doesn't stay warm all the time. Indirects are pretty pricey, but very efficient at their job.

You could install a separate gas (or oil) fired water heater, but might run into problems with the flue vent... what would you do with that ? Maybe your existing chimney could be used, maybe not...

All that said, I think the settings on your aquastat are whack... 190 high is probably OK, but I would run that back to 180. That setting ONLY controls the heating to the home. The LOW setting is the temperature that the boiler will 'maintain' when it is being kept warm to heat the domestic hot water. I would roll that back to 140, and set the diff to max ... 20 or 25 ...

Do you know if there is a mixing valve on the boiler ? Most codes require them as they reduce the risk of scalding injuries. If you don't have one, with that LOW setting at 170, you run a very real risk of scalding injury... VERY HOT water can be produced !

By running the LOW setting to 140, you _may_ find that the coil in the boiler won't provide you with enough hot water, but try it anyway ... it will save you money.

If you aren't sure if you have a mixing (or 'tempering') valve on your boiler, take some pics and set up a free account at www.photobucket.com and upload the pics there. Provide us with a link to the photos and we can tell what you have.
 
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Old 04-11-08, 04:02 PM
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I agree with Trooper. I also suggest looking very hard at solar domestic hot water (SDHW). There are pretty good tax credits and even utility company rebates available. If your house is reasonably well-suited for solar, and you are already paying through the nose for DHW, then payback on SDHW can be pretty short -- like 3-4 years.

Check out dsireusa.org for a list of current incentives, rebates etc. in your state.
 
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Old 04-11-08, 05:19 PM
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Electric probably would cost more seeing that I pay around .22/kWh so that's out. I'm in the Northeast with only morning sun hitting my property (front of house) the rest of the day I'm pretty much shaded by trees. I think the only option is an oil powered water heater correct?

Thanks for the tip on changing the aquastat settings. I switched it to 160 high and 130 low with a 20 differential (mine doesn't have a 25). Now that I know the high controls the heat and the low controls the hot water, what does the differential control?
 
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Old 04-11-08, 05:40 PM
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You might still run into flue venting problems with an oil (or gas?) fired water heater. Can your chimney handle two appliances ?

Research INDIRECT WATER HEATERS ... personally, I think that's your best bet.

Not sure I would have dropped it to 160 HIGH ... now that the weather is warming up, won't be a problem, but when it gets cold out again next year, you might not get enough heat into the house. Keep that at least 180 ...

Try the 130 on the LOW, but again, you may not get enough hot water... I'd start with the 140 I recommended... is there a tempering valve on the hot water supply near the boiler ?

The differential: Lessee how to explain... it's the 'width' of the control range. If it's set at 20, and the low setting at say 130, when the boiler cools to 120, it will fire up and heat to 140 (20 degree differential). The boiler will always drop TEN degrees below the LOW setting before it runs. So, if it was set at 140, it would drop to 130 before it fired. If you had the diff set at say 15, it would then run up to 145 and shut off.

The higher differential will allow a slightly longer run time, which is more efficient, but a LONGER time between runs. In other words less runs. With the diff set at 10, you would get a lot of short runs, with little time between them. In the end, it's probably close to the same amount of run time, but you will save a percent or three with a longer run.

Where you will save is by dropping the LOW setting to 140. (I'm not saying a LOT, but it should be noticeable)
 
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Old 04-11-08, 05:53 PM
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One mroe thing I wanted to add:

The HIGH setting has a differential also, but it is FIXED, so there is no adjustment for it.

The diff setting only has affect on the LOW setting.
 
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Old 04-11-08, 06:54 PM
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Indirect water heater would be the way to go. No additional venting, very efficient way to make hot water, etc.

There are probably utility or other rebates available that would help, even if you use oil (e.g., electric company efficiency program). dsireusa.org tracks tons of them.

Weil-McLain makes indirect water heaters, at least one of them (Ultra) quite good. http://weil-mclain.com/products/disp...Water%20heater
 
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Old 04-11-08, 08:07 PM
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Summertime Timer?

I was looking at the INTERMATIC ST01C timer and thinking how easy it would be to install right beside my burner cutoff switch. (In parallel).

I see people using timers on electric hot water heaters all over the place.
Got me thinking that maybe a timer could be used on my HS Tarm (with 'tankless' coil).
It's got a 76 gallon water jacket and I could do some more pipe insulation and slow down it's heat loss.?.

What do you guys think? Worth $30 to try out the idea?
 
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Old 04-12-08, 01:32 PM
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76 Gallon water jacket?

You want to save some real money? Scrap that monster & get something with far less water to keep hot. To get that much water up to operating temp is going to take a while.
 
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Old 04-12-08, 04:22 PM
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"Scrap that monster"?

A few years back, we got some estimates for removing it (not replacing it). None under $1,200 !
(Since it's 1/4" steel, we had a welder come in and make repairs. The repairs cost a lot less than $1,200).

So, I just may be keeping it for a while longer.. Plus, it has some features that makes it a keeper.
It can burn wood or coal. Right now, I could toss some scrap wood in and have hot water all night long.

More importantly, if (or should I say when) heating oil hits $15 a gallon, that HS Tarm can heat our house burning wood, newspaper rolls or even junk mail.
 
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Old 06-05-12, 08:25 AM
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Cool Same situation/opportunity...Summer time reduction of cost to heat hot water

I have a Weil steam burner, live in MA, and the tankless coil. I also am thinking about timers (or better yet, timers with a wireless ON/OFF switch for turning on the furnace/coil in summer when you need to run the dishwasher or shower.

I have bad winter sun exposure but okay summer sun exposure and room for 1 or 2 solar HW panels on a 1st floor sunporch roof. I was thinking of switching the coil for a stainless tank in tank indirect fired, fed by a drainback or antifreeze powered HW panel or two and tank. To save costs, I am hoping to go with used panels and maybe used stainless tanks.

I am hoping the undersizing of the HW panels will be offset by less worry of summertime overheating of the water...and less use of the furnace to heat summertime indirect tank water.

Does this plan seem okay, anyone?
 
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Old 06-05-12, 09:13 AM
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The previous owner of my home had done the switch from the coil to a seporate electric domestic hotwater tank. They however completely shut off the coil and ran always on the tank.

Space permitting, here is what I would do;
Pick up an eletric hotwater tank suitable for the demand. Tie it into the the output of your coil (with valve to on both feeds so you can turn one off, the other on).
Summer time, when you shut down the boiler, switch to the electric (or other source) and when it comes time to fire up the boiler again, you can shut down the tank and go back to the coil.

Should the coil plug up, you can leave it closed and run on the tank.

Based on the flyers I was looking at the other day and all DIY work;
Eletric hotwater tank: ~$300
Copper pipe fittings/valves: ~$25
Power cable for tank: ~$20
220V breaker: ~$30

Assuming you have all the tools, your looking at roughly $375 for stuff, plus any tools you do not already have.

The eletric hot water tank can be replaced with any source of hot water, but this is probably the easiest and quickest solution I can think of (space permitting).
 
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