Add electric water heater to existing boiler system

[Siestamagic]

Hello all,

I have an existing oil hot water furnace (a New Yorker boiler) that doubles to heat my baseboard radiators (during cold Canadian winters), as well as supply hot water to faucets throughout my home. I have a Kenmore Power Miser 6 55 gal electric water heater that I would like to add to my domestic hot water system.

Reason for adding a water heater - filling the tub takes a very long time because of shutting the faucet off after 1 to 2 minute, waiting for the furnace to heat the water back up and then repeat the process many times before the tub is ready for use.

My boiler currently has 5 connections.
1. Cold water inlet at the base of the boiler (radiant heating supply).
2. Hot water outlet for my heating system (radiant heating).
3. Cold water inlet at the side of the boiler (domestic).
4. Hot water outlet at the side of the boiler (domestic).
5. A line from the top of the boiler, T'd off to a relief valve and up to an expansion tank.

I need to know what is the best way to add the water heater into this system or if anyone has any other suggestions. My home has 1 and 1/2 baths. My home has a municipal water meter on the supply line.

My Questions - can I and should I close off the hot water outlet (connection 4. from above) and T in my hot water outlet from the electric water heater to the domestic line? If I did, would I need another expansion tank for the electric water heater?

Or do I tie my 2 systems together and would the existing expansion tank (at the end of connection 5.) be sufficient for this type of combined system? If so, how would I tie the electric hot water heater into the existing system?



Thanks everyone in advance.

 

[bryant2400]

I'm also interested in this

 

[KULTULZ]

...and would the existing expansion tank (at the end of connection 5.) be sufficient for this type of combined system?

I can't help you other than the expansion tank(s) need to be sized for the system(s) capacity, i.e. the tank has to have the capacity to absorb total thermal expansion.

There is usually a sizing chart available online.

 

[johnjh2o]

The way it should be done is connect the outgoing hot from the coil to the cold water inlet on the water heater. Then connect the hot side of the water heater to the line feeding the home. What you will be doing is preheating the water going into the water heater. Saving on the electric bill.

 

[Siestamagic]

Thank you John,

That is the way I hoped it would work. My only concern is tthe placement of the expanion tank. The expansion tank is part of my existing boiler system and is connected directly to the boiler.

I am wondering if the expansion tank would utilized by the hot water heater. Can the water be forced back through the boiler and up to the expansion tank qhen needed?

Kultulz, I will check the figures and try to determine if my current expansion tank is sized right for my system, as well. Now is there such a thing as having an expansion tank that is too big or would it be acceptable to simply add another expansion tank to the new hot water heater loop?

 

[johnjh2o]

The expansion tank on the boiler has nothing to do with the domestic hot water system. You will also need a small tank on the water heater.

 

[frodo]

you will need to set the t-stat on the boiler water below the setting on the water heater
or it will act as just a storage tank

 

[johnjh2o]

you will need to set the t-stat on the boiler water below the setting on the water heater
or it will act as just a storage tank

His problem was that the coil couldn't keep up when he was filling the tub. A storage tank is what he needs.

 

[frodo]

His problem was that the coil couldn't keep up when he was filling the tub. A storage tank is what he needs.

why cant the coil keep up. that is the real question.

that should be no problem for a boiler/water heater package system

i think he needs to **** can the old oil burner and up grade to a efficient system, instead of dicking around with a water heater.

i would bet to assume, his house is not as warm as it used to be and his bill for oil keeps going up every year

boiler tubes are most likely trashed, water jacket full of sediment and crap

 

[Siestamagic]

Its true, my system is getting to the end of its life expectency, from what I am told by salesmen. This boiler is 18 yrs old and the burner was replaced about 5 yrs ago, no other repairs. Realistically, how long should I expect to get out of a late 90's boiler? I was hoping for a few more years out it.

The water supply was never lasting long enough to fill a bathtub with hot water though, without throttling down the supply to about a quarter open or running the shower head to fill it.

The issue does seem to worsen during winter when the system is heating the hot water radiators as well. It is serviced every year but a reputable company. Would that keep the water jackets clear of sediment.

 

[frodo]

sounds like you needed a storage tank all along

18 years, its life is up, replace it with a high effency unit

 

[Matt30]

Start with a coil change. 18 years of sediment more then likely has that tube almost choked off, now giving you less water volume to heat.

Also, no mixing valve? What temperature does your boiler run at?