Another thread about conversion...

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Old 04-30-14, 07:06 PM
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Another thread about conversion...

...from oil hot water to electric.

This is my furnace...



...I know, it's old...but the people I bought the house from had a stack of receipts from having it serviced every year.

In the pic below, you can see the cold line coming in on the right and teeing off before the valve to the inlet of the furnace/boiler...



...which presents question #1...why is the cold line in also going to that green cast iron piece and also up to the tank mounted above? Is it to feed the baseboard heaters?

Question #2...to convert to electric, I can just disconnect the cold from the furnace and plumb it to the inlet of my tankless hot water heater...Do I then just plug the inlet and outlet on the furnace?

I plan to redo all the plumbing anyway, so I could just set up the furnace to be a back up to the tankless.

Question #3...why do I need this tank?




I appreciate you looking and thanks in advance for your input!
 
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Old 05-01-14, 06:08 AM
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Haha...250 views and I stumped everyone!
 
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Old 05-01-14, 06:55 AM
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No sir... nobody is 'stumped'.

We are all volunteers here and answer when we can. You don't really expect us to stay up all night waiting for someone to post a question and jump on it as soon as they do, do you?

We answer when time permits...

I'll get back to you this evening if nobody else has.
 
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Old 05-01-14, 08:39 AM
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hi JP –

I’m no expert to say the least, just a newbie, and there are guys here that can explain this extremely well. But that overhead tank is an “Expansion Tank” (I have one like that) which has some trapped air inside it. This allows for the normal expansion of the water in the boiler system as it is heated. The air is compressible so it will compress smoothly. You have to have an Expansion Tank.

I think the valve on the pipe up to the Expansion Tank is there so you can shut off the water supply to it, and isolate the tank so it may be serviced. (I don’t have a shutoff valve there – I should, I guess someone took a shortcut in my case.)

You have the old-fashioned tank like I do. The modern ones have a diaphragm separating the air from the water.

I don’t know what that green thingy is LOL – but that will be a piece of cake for the experts here.


p.s. I just noticed something, don't know whether it means a thing lol, but why is that shutoff switch so high up? Oh - maybe it's not as high as it looks? I was just wondering if it can be reached without a ladder? Probably OK.
 
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Old 05-01-14, 06:50 PM
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JP,
Are you talking about going to electric heat or just hot water.
If you want to use your boiler as a backup why disconnect it.
The cold water line goes into the green valve because that's where your system is being fed.
The expansion tank is necessary to receive the heated water as it expands when it heated, just like an overflow in a a car. It's the same principal. Without it the water heated water would have no where to go and your relief valve would blow off when the pressure reached 30psi.
 
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Old 05-01-14, 09:28 PM
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Originally Posted by NJ Trooper
No sir... nobody is 'stumped'.

We are all volunteers here and answer when we can. You don't really expect us to stay up all night waiting for someone to post a question and jump on it as soon as they do, do you?

We answer when time permits...

I'll get back to you this evening if nobody else has.
Take it easy big fella, I was just messin' around. I understand how a forum works. I would appreciate your input when you have time.

Originally Posted by zoesdad
hi JP –

I’m no expert to say the least, just a newbie, and there are guys here that can explain this extremely well. But that overhead tank is an “Expansion Tank” (I have one like that) which has some trapped air inside it. This allows for the normal expansion of the water in the boiler system as it is heated. The air is compressible so it will compress smoothly. You have to have an Expansion Tank.

I think the valve on the pipe up to the Expansion Tank is there so you can shut off the water supply to it, and isolate the tank so it may be serviced. (I don’t have a shutoff valve there – I should, I guess someone took a shortcut in my case.)

You have the old-fashioned tank like I do. The modern ones have a diaphragm separating the air from the water.

I don’t know what that green thingy is LOL – but that will be a piece of cake for the experts here.


p.s. I just noticed something, don't know whether it means a thing lol, but why is that shutoff switch so high up? Oh - maybe it's not as high as it looks? I was just wondering if it can be reached without a ladder? Probably OK.
Thanks for the reply.
The switch is not as high as it looks, plus I have another at the top of my basement stairs.

Originally Posted by spott
JP,
Are you talking about going to electric heat or just hot water.
If you want to use your boiler as a backup why disconnect it.
The cold water line goes into the green valve because that's where your system is being fed.
The expansion tank is necessary to receive the heated water as it expands when it heated, just like an overflow in a a car. It's the same principal. Without it the water heated water would have no where to go and your relief valve would blow off when the pressure reached 30psi.
Thanks for the reply.
So, after the cold water enters the green valve does it go up or down?
You can see the fat copper pipe coming out of the top of the green valve and it appears to be feeding my baseboard heaters.
 
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Old 05-02-14, 09:45 AM
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It goes up to feed the baseboard heaters being circulated by the pump on the return line that goes into the bottom of the boiler to get reheated.

On a call for heat the boiler comes on and when there is enough temp in the boiler the pump comes on to circulate the heated water.
Since you're getting your hot water from the boiler also it is possible that your pump could come on first and then the burner if the water is already hot enough.

Because you get your domestic hot water from the boiler also the boiler maintains a certain temp to assure you always have hot water which means your boiler will run even in the summer to maintain temp. even though you're not calling for heat.

Without the tankless coil the boiler could be set up as a cold start boiler that would only run on a call for heat which means it would not run in the summer at all.

I hope this helps to understand the system.
 
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Old 05-02-14, 04:16 PM
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Originally Posted by spott
It goes up to feed the baseboard heaters being circulated by the pump on the return line that goes into the bottom of the boiler to get reheated.

On a call for heat the boiler comes on and when there is enough temp in the boiler the pump comes on to circulate the heated water.
Since you're getting your hot water from the boiler also it is possible that your pump could come on first and then the burner if the water is already hot enough.

Because you get your domestic hot water from the boiler also the boiler maintains a certain temp to assure you always have hot water which means your boiler will run even in the summer to maintain temp. even though you're not calling for heat.

Without the tankless coil the boiler could be set up as a cold start boiler that would only run on a call for heat which means it would not run in the summer at all.

I hope this helps to understand the system.
Thanks for the reply spott, that does help a lot.

I don't want the furnace to run at all in the summer, one of the reasons I'm putting in a tankless water heater. How do you set up a cold start boiler?
 
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Old 05-02-14, 05:25 PM
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That aquastat on the boiler that says Dahl. You have a high limit and a low limit. To get it to run less turn your low limit down as low as it will go. Depending what control you have you may be able to eliminate the low limit altogether.
Boilers that don't come with a tankless coil have cold start aquastats already installed.
You could put a new cold start aquastat on yours. Cold start has only a high limit. There is no low limit control knob.

Realize you cannot do this until you stop using the boiler for hot water. After you change your hot water you can simply shut the switch off in the summer.
 
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Old 05-02-14, 07:30 PM
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JP, tell us what model the aquastat is, if it's an L8124 it's pretty easy to convert (and fully reversible should the need arise).

By the way, when you cut the domestic pipes from the boiler, don't solder caps on the abandoned pipes. Just slip fit a cap. This advice from several of the water heater manufacturers, has to do with pressure buildup inside the coil... although, IMHO, it's not likely to be a problem... but it's always a good idea to listen to the manufacturers.
 
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Old 05-03-14, 07:52 AM
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Thanks for the replies guys...I appreciate the input.

NJT...this is what it says on top of the aquastat...

 
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Old 05-03-14, 08:05 AM
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That's an 'oldie' for sure...

I can't locate a schematic diagram on-line for that and can't advise on how to modify for 'cold start' without one.

I can tell you that the entire aquastat can be replaced with an appropriate cold start aquastat though.

Spott, would you happen to have a diagram of the 8024 handy?
 
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Old 05-04-14, 07:26 AM
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Thank you again NJT...I don't mind changing the aquastat, but if I swap it to a cold start one...will I still be able to use the furnace/boiler as a back up?
 
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Old 05-04-14, 07:54 AM
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Not sure what you mean by 'back-up' ?

My understanding is that you want to install a separate domestic water heater not requiring the use of the boiler to heat the domestic. This would involve cutting the domestic piping, re-routing to the new water heater and abandoning the tankless coil inside the boiler.

Did you have a different plan?
 
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Old 05-04-14, 09:32 AM
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I don't happen to have one either.
If you intend to use your boiler as a backup for domestic water you simply cut in new hot & cold pipes with shutoffs to the new tank and valve off the domestic boiler lines to the boiler.
If you intend to use the boiler as a backup you need an aquastat with a low limit. A cold start only reacts to a t-stat call for heat.

Trooper I did find a company selling that aquastat for 525.00. I think the company was Jesse James inc.
The silver lining was FREE SHIPPING.
 
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Old 05-04-14, 09:42 AM
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valve off the domestic boiler lines to the boiler.
Only if there is provision for expansion! If you leave water in the coil and valve off the inlet and the outlet there would almost definitely be problems from the water in the valved off coil possibly bursting the coil... I know unlikely, but POSSIBLE, so best not to 'divorce' the coil from the rest of the system with valves.

One thing I definitely am against is leaving 'dead ends' in a domestic water system where may not be flow for extended periods of time... makes for a nice neighborhood for the creepy crawlies that exist in most domestic water systems (in non-harmful amounts typically) to live, breed, and proliferate.
 
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Old 05-04-14, 09:43 AM
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a company selling that aquastat for 525.00
Yikes! Highway robbers!

It can be had for less of course, under $200... but it makes no sense to replace with same when there are many modern aquastats that will replace it easily.
 
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Old 05-04-14, 01:32 PM
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Originally Posted by NJ Trooper
Not sure what you mean by 'back-up' ?

My understanding is that you want to install a separate domestic water heater not requiring the use of the boiler to heat the domestic. This would involve cutting the domestic piping, re-routing to the new water heater and abandoning the tankless coil inside the boiler.

Did you have a different plan?
The plan is to plumb in an electric, tankless water heater so I won't need my furnace for hot water...but in the case of water heater failure, I can have the plumbing setup to only have to pop in a couple shark bites to get the hot water going temporarily from the boiler.
Looks good on paper anyway haha
 
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Old 05-04-14, 01:43 PM
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Why don't you leave the boiler the way it is and just pipe in the new hot water heater as though there was nothing else there. Just put cold and hot water shutoffs on the new tank in case you need the boiler and not the tank.
You already have a shutoff on the cold water supply to the coil in the boiler I presume. When using the new tank just shut it off.

With the shutoff valves in place you essentially have two different systems.
It's really that simple unless I'm missing something.
 
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Old 05-04-14, 02:11 PM
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Just put cold and hot water shutoffs on the new tank
And again the caution... if you do this, do not 'dead end' the water heater because if you turn it on and forget to open the valves, chances are pretty good you will burst a pipe in the water heater from pressure buildup as the water heats.
 
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Old 05-04-14, 06:13 PM
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Originally Posted by spott
Why don't you leave the boiler the way it is and just pipe in the new hot water heater as though there was nothing else there. Just put cold and hot water shutoffs on the new tank in case you need the boiler and not the tank.
You already have a shutoff on the cold water supply to the coil in the boiler I presume. When using the new tank just shut it off.

With the shutoff valves in place you essentially have two different systems.
It's really that simple unless I'm missing something.
I think you're right, it is that easy...I think, haha...I am redoing all the plumbing, so I could easily set up the boiler to be on "stand by" without actually being hooked up.
 
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Old 05-04-14, 07:35 PM
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JP,
Not to over simplify but even if you weren't redoing the plumbing it is a fairly simple job.
Get the location of the new tank. Shut the water down, cut a tee in your cold water and hot water lines. Install a shutoff on each and attach to the new tank.

Trooper made a very good point that I sometimes take for granted.
Make sure you OPEN both valves before turning on the tank.
I assume people would do this but Trooper, being on this site forever and realizing that what seems natural to us doesn't to people looking for help is much more cautious and that is why people like him are invaluable to sites like this.

One thing I will caution you on is never power up an electric hot water without water being in it.
On a conventional tank if it is not full of water you will immediately burn out the elements.

Good Luck,
 
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Old 05-05-14, 06:39 PM
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Thanks spott, I'll post some pics when I actually do the conversion. It will be a little while as I'm still gathering materials, fittings, and of course knowledge.

I really appreciate the input from you and NJT, thanks very much!
 
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Old 08-28-14, 01:06 PM
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I started my project last week, just doing a little at a time as my time permits...

 
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Old 08-29-14, 04:52 PM
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Old 08-30-14, 12:43 PM
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Hi JP –

I’m no plumber or expert of any kind, and maybe to my embarrassment the answer is staring me right in the face – but why do you have two ball valves in series on the top piping without anything in between?
 
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Old 08-30-14, 06:46 PM
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I'm sure you're aware that you need at LEAST a 200 AMP main electric service panel, and that you will be installing THREE double pole 40 AMP breakers in that panel, and that you need THREE sets of 8 gauge wires going to it, correct?

Will you be doing the wiring? If so, are you qualified? or will you have an electrician come in to do that part?

I think you should also know that unless that unit is installed by licensed plumber and electrician that the warranty will be VOID in the event the unit goes down... they WILL ask for proof.
 
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Old 08-31-14, 09:39 PM
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Originally Posted by zoesdad
Hi JP –

I’m no plumber or expert of any kind, and maybe to my embarrassment the answer is staring me right in the face – but why do you have two ball valves in series on the top piping without anything in between?
Haha good observation!...short answer...I'm not a plumber! haha...I just plain forgot the water heater lines had valves. There is no need for 2 valves in either line, but they are already plumbed in, so I'll leave it.
 
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Old 08-31-14, 09:51 PM
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Originally Posted by NJ Trooper
I'm sure you're aware that you need at LEAST a 200 AMP main electric service panel, and that you will be installing THREE double pole 40 AMP breakers in that panel, and that you need THREE sets of 8 gauge wires going to it, correct?

Will you be doing the wiring? If so, are you qualified? or will you have an electrician come in to do that part?

I think you should also know that unless that unit is installed by licensed plumber and electrician that the warranty will be VOID in the event the unit goes down... they WILL ask for proof.
Yes sir, I am aware...my house has had all the electrical upgraded to 200 amp service before I bought it.

While I am able to do the wiring, I will be having a licensed electrician do it.

I have read warranty conditions and I am prepared for any issues with the unit, I know a few people who are able to service it if need be.
 
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Old 09-01-14, 07:27 AM
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OK, good... most ppl aren't aware of the power demands of these heaters.

What size is that piping? Looks like 1/2" ? and those 'flex lines' , what size?

By the way, there is a 'water heaters' forum in the "Plumbing" section. This isn't really boiler related. I will be moving this in a little bit...
 
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Old 09-01-14, 05:51 PM
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I'm not a plumber! haha...I just plain forgot the water heater lines had valves….
Yeah – but did you ever install a ball valve so you couldn’t move the handle to close it? Haha – got ya didn’t I ? Whoops
 
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Old 09-01-14, 06:52 PM
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Originally Posted by NJ Trooper
OK, good... most ppl aren't aware of the power demands of these heaters.

What size is that piping? Looks like 1/2" ? and those 'flex lines' , what size?

By the way, there is a 'water heaters' forum in the "Plumbing" section. This isn't really boiler related. I will be moving this in a little bit...
The copper piping and the water heater lines are 3/4"...the pex that will be coming out of the manifolds will be 1/2".

I didn't notice the water heater section until after I started this thread...by all means, if you are able to move this thread to that section, thanks!
 
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Old 09-01-14, 06:59 PM
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Yeah – but did you ever install a ball valve so you couldn’t move the handle to close it? Haha – got ya didn’t I ? Whoops

Hahaha, no sir!...I have never done that!
 
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Old 09-01-14, 07:13 PM
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Oh my!!!!! all I can say.....!!!!
 
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Old 09-03-14, 04:24 PM
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Thanks!...I think...hahaha
 
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