Electric boilers and indercts

Plumbob_3

Due to the price difference propane vs. electric we install many electric boilers.



Any thoughts on indirect water heaters and electric boilers? pros.......cons?



Thanks

Unknown

Well,,,

Depending on the current electrical rates, what would be gained(for them) with an indirect? No chimney?



Both have immersion elements, and have almost a 100% efficiency rating,, so if they are NOT TOO concerned over who is supplying "their" electricity, environmental issues wont bother them. :-).

Mark Eatherton

Only one correct answer to this question....

And 'Ive used it so many times, I've decided NOT to use it agin. At least in this post. If someone DOESN'T know "the ONLY correct answer" Ask, I'll be glad to share. Jeez, it would have been easier to just SAY it... Oh well.If your electricity cost are cheap and stable, (hydro? Nuke? Solar?) AND you have the ampacity available, you can put in an infinitely adjustable system. 100 to 1 % in 1% increments is technically possible. But if you want to save green, be green and look GREEN, go solar. Small systems work GREAT for handling most (2-3 people) loads, but you have to either have ampacity to do it "instantaneously", or have LOTS of storage with a small amp system and let everyone know that system recovery is slow, so if you can spread the loads out over time (usually achieveable").Any waste heat recovery can further reduce other low temperature loads, by a minimum of 20%, and potentially as much as 60% depending (DANg, I used THAT word...." THe cost of that conservation system alone SHOULD have a 50% tax credit for it. It's a conservation effort with an excellent ROI, but I digress... You asked about S.A. DHW with an electric boiler. Yes, it can be done, and I would recommend the use of a reverse indirect. It is THE most efficient heat exchange/storage unit on the market today (as a tank/HX combo), and worth every penny. You can actually "buffer" the electric heat source. 100% efficient.Un-disputable. ME

Plumbob_3

green

I really wasn't looking for a lecture on being green. I have installed

solar systems before, I live in the pacific northwest, very little sun

to begin with. This particular house is on a north slope, (even less

sun), their electric is hydro, it is stable,.  The price of propane is

not stable in our area.





thank you

SpeyFitter

Why?

I think using an electric boiler to heat an indirect tank is a little redundant in my opinion. You're better off using an electric hot water tank if that's the case. If you use an electric hot water tank, you won't have to work the elements in the boiler so hard to heat the water up to a hot enough temperature to make a difference in the indirects temperature. Also, most electric boilers have simple controls built in, some with outdoor resets involved. If you can focus the electric boiler on just heating, the built in controls will often suffice for many installations (or should anyways). If you use it to heat an indirect, now you need to factor in some real controls to deal with water temps (assuming you'd use the electric for low temp heating i.e. radiant). The other thing is you can save yourself a pump if you just use one pump with the boiler, and an electric tank which requries no pump. Otherwise you'll either need 2 zone valves and a pump, or 2 pumps, to do the indirect and regular heating load.

Now having said that, the one benefit of using an indirect is you can get stainless steel models which offer increased longetivity over your conventional electric hot water tank.

My question for you is have you actually priced the difference between electricity and propane on an apples to apples basis? 

 

Plumbob_3

Thanks Scott

Our Electric rates run about 4 1/2 cents per kilowatt hour, If I remember correctly the break even point with propane per btu was around  $1.60 a gallon, we haven't seen that in sometime. Propane around here runs about $2.60. To add to the cost of fuel  this project is on an island. It does have ample power though.



I have done   wood boilers with electric backups and the systems have had indirects included. I thought about the extra pump, extra piping, cost of the ss tank, as well, but was not sure if there may be some benefit, like a quicker recovery rate, or........heck I couldnt think of any benefit. So I knew that if there was a place I could get good feedback it would be here.



Our groundwater around here is typically  very cold, so on demands around here have been a  poor option at best.

EricAune

Thermolec

Check into Thermolec boilers.  You will get a stainless exchanger, outdoor reset and the option of a dual temp board.  I have done a couple jobs with parameters such as yours.  Depending on the heat load, using the boiler can be a great system over a tank type h2o heater.



I am not sure of the electric boiler you use, be sure to check the max supply temp it is capable of.  Some manufacturers make nice units for radiant but will not put out the temps desired for an indirect. 

hot_rod

a lifetime electric tank

I think HTP still offers the Everlast stainless electric tanks. If you need quicker recovery maybe up size the elements to 5.5 KW or change the controls to fire both elements at once. It may be less $$ and just as much KWH as a boiler fired indirect.



hr

SpeyFitter

Thermolec - hard to go wrong

The company I work for uses Thermolecs as well for any application requiring an electric boiler.  Great boilers, and as was said, they have an ODR and you can get them with a S/S heat exchanger.

Royboy

just had the same issue/question

arise from a potential client who wants me to install equipment he purchased - an electric boiler, a pump station assembly, and an indirect. my response to him, slightly toned down because I didn't want to insult his choice, was that I could see no significant upside and considerable downside to using an indirect tank with an electric boiler as opposed to just using a conventional electric water heater.



as I see it, the indirect requires a more expensive tank, a heat exchange coil, a pump and/or zone valve, and more complex controls for the boiler. that's the equipment downside. operationally there is both increased operational costs to power pump/zone valve plus added heat loss from the indirect piping.



when I asked why he had gone this route, he said the boiler supplier had said it would be "more efficient." I tried to convey that I thought it would be the opposite.



I really can't see any virtue to an electric boiler indirect, unless its recovery rate, and I think there are easier/better ways to deal with that.



Roy

Devan

My set up

Plumbob,I had the Thermolec, for my RFH, it gave me problems after two years, bad contactor, and was noisey. Support horrible. Last winter it started to leak. I got rid of it and replaced it with a Seisco. I've been using Seisco for electric tankless for 10 years, not one problem.I also had solar hot water preheating the tankless.So what I did was install a Seisco SH-28 kw unit , added the extra pump and piped it to the upper coil of a dual coil tank.My electric rates are higher than yours , but they are stable, plus my bill is very low in the summer from the solar, so I don't mind. Don't forget the yearly maintenance is nothing, and no exhaust pipe or potential CO issues.



Also I plugged in a Taco PC 700 w/ODR into SR relay box for boiler reset. Very basic, but it works

Radman

Water conditions

A good pro of  this situation is that if the incoming water conditions are hard, the indirect can be potentially less susceptible to scaling than an electric element.

Power for power, it seems a wash.   Is it better to use a SST indirect, and have greater recovery or go with an electric automatic storage water heater, replace the occaisonal element, and endure slow recovery? 

EricAune

Devan,

I have had the exact opposite experience it sounds.  I have had nothing but problems with Siesco units and have been replacing them with Thermolecs for quite some time.  Are you piping them in primary/secondary or using hydro-separators?  The flow through these little exchangers is very low.  Have you not had any problems with the plastic connections or constantly going out on high limit?



These are just some of the problems I have encountered, I am sure they have their place...just not on any of my jobs. 



PS, another reason I wont use them is their proficiency to sell to local utility companies in our state.  The utility buys down the cost in order to offer them to their customers at a huge discount that no contractor could ever compete with.  Puts a bad taste in ones mouth. 

Plumbob_3

Good stuff here guys

Would I get quicker recovery? Seems like I would but I cant put the pieces of the puzzle together that tells me yes I would. Kinda been a brainteaser for me.