Hi, I live in Long Island, NY. My current heating system is a 50+ year
old American Standard boiler with a Beckett oil-fired burner. Attached
to it is an uninsulated indirect water heater of unknown brand (which
is probably as old as the boiler). Most of the system is as old as the
house, which was built in the early 50s (the burner and a couple of the
circulators are fairly new).

For some reason, the previous homeowner (who was also the homebuilder)
connected the indirect water heater to the hot water coil of the
boiler, rather than using the recirculated boiler water. The system had
been working fairly well, although I suspect not at top efficiency (we
had insulated the water heater using a fiberglass water heater blanket,
but there was still some heat leakage out the top).

Anyway, recently, we've been having problems with the boiler pressure
triggering the pressure relief valve. After I empty the expansion tank,
the pressure gauge goes down to a more reasonable level; a couple of
weeks later and the pressure is high again. Our serviceman came out and
told us that there is a crack in the hot water coil (I'm not sure how
he concluded this, as I wasn't home at the time, and I didn't think to
ask). Now, since indirect water heaters don't require a hot water coil
(and when I tried to run our domestic HW directly through the coil, the
pressure was awful), I'm thinking I can just plug the HWC and attach
the water heater directly to the boiler. Now the questions ensue:

1. Is the conclusion about the cracked hot water coil valid? Is there
anything else that might cause this situation (boiler temperature is
being regulated properly at 160F)?

2. I'm thinking that since I'm doing some major work on the system, I
might as well replace the indirect water heater at the same time (I
don't want to get involved in replacing the boiler; I know it's not the
most efficient but that would incur enormous expense which would
probably not be recovered for a couple of decades; the sytem has been
fairly reliable except for this issue). I've noticed there are two
major types: most have a large recirculated-water tank with a coil for
domestic water; however, Phase III (and possibly other) heaters have an
outer and inner tank (this is how I had assumed they were all
constructed before I started doing research). Is there any advantage of
one over the other? The Phase III heaters have a much larger domestic
tank than recirculated-water tank.

3. The installation instructions for the Phase III heater explicitly
specify not to plug the old hot water coil (their exact words:
"Plugging tankless coil inlet and outlet will [sic] result in severe
personal injury, death, or substantial property damage."). Now first,
it seems to me that if the coil is completely purged of water, the only
thing in it will be air, and expanding air won't be enough to rupture
the coil. Additionally, I've seen similar systems in other homes where
the HWC HAD been plugged; also, since our coil is already cracked,
additional damage will be minimal or non-existent. Thoughts?

4. The house is a two-family home; figure average occupancy is 6 people
(adults+children). Any way I can easily calculate the size heater I
need?

Post responses to the groups, please; this email address is now owned
by the spammers.

Thanks,

Steve

Steve wrote:

Hi, I live in Long Island, NY. My current heating system is a 50+ year
old American Standard boiler with a Beckett oil-fired burner. Attached
to it is an uninsulated indirect water heater of unknown brand (which
is probably as old as the boiler). Most of the system is as old as the
house, which was built in the early 50s (the burner and a couple of the
circulators are fairly new).

For some reason, the previous homeowner (who was also the homebuilder)
connected the indirect water heater to the hot water coil of the
boiler, rather than using the recirculated boiler water. The system had
been working fairly well, although I suspect not at top efficiency (we
had insulated the water heater using a fiberglass water heater blanket,
but there was still some heat leakage out the top).

Anyway, recently, we've been having problems with the boiler pressure
triggering the pressure relief valve. After I empty the expansion tank,
the pressure gauge goes down to a more reasonable level; a couple of
weeks later and the pressure is high again. Our serviceman came out and
told us that there is a crack in the hot water coil (I'm not sure how
he concluded this, as I wasn't home at the time, and I didn't think to
ask).

SNIP

The other possibility is that the boiler feedwater valve is leaking
(i.e., not closing tightly) allowing a trickle of water into the
boiler day and night. Look for a shutoff valve so you can isolate
that as a cause.

former LI'er

My thought on the cracked coil would be that if it is cracked you
should see water leaking. And if it is cracked, then you will most
likely be getting boiler hot water into your domestic hot water. Is
your hot water brown or dirty looking?
As for the pressure relief valve. Check your automatic fill valve. It
may need to be replaced. Depending on your water, the valve may be
stuck open a liitle causing your boiler to fill and raise the pressure.
I'd replace it or better yet, open it up and look to see if there is a
lot of crud in it.

If the boiler is 50 + years old you still may want to consider
replacing it. I replace them, depending of the BTU's and # of zones,
for around 3 - 4K complete. Your savings should be made up in a couple
of years because of the effiency.

A new 40 to 50 gal indirect DHW can run about 600 - 1K depending on
model.

Paul

whether you replace this old boiler and water heater or continue
inefficiently operating it as an antique with a full set of new safe
replacement controls and energy star rated circulating pumps is up to
you.
who: i'm not the hvac expert for this.
what: is the combustion efficiency of your model number? maybe 50-60
percent?
where you live, the climate: what is the energy source of least expense
for this heating task in your city?
when: you need to do this is either at the hvac company's convenience
instead of rushing the job, while you monitor the pressure and leakage
problems and get a headache, or as soon as you shake some money out of
your budget for this home improvement.
why: for year-round comfort and energy savings.
how: keep doing the homework.
is it still true that there are no high efficiency boilers for oil,
only natural gas?
can you install central air and an efficient gas furnace? nice central
air conditioning may be the wonderful summer benefit that awaits you.
the new insulation package you install into your home will affect your
btu calculations.
see:
http://www.buildingscience.com/resources/

On 8 Mar 2006 11:58:14 -0800, someone wrote:

My thought on the cracked coil would be that if it is cracked you
should see water leaking.

Water leaking to WHERE? The coil is internal to the boiler chamber,
it is surrounded by boiler water, where would one see a leak?
(Really, if there is someplace, I'd like to know, I've seen this
situation and there was no visible leak anywhere external.)

And if it is cracked, then you will most
likely be getting boiler hot water into your domestic hot water. Is
your hot water brown or dirty looking?

Not necessarily. The pressure would be the other way around, as
domestic water is often around say 60 psi and a low pressure
residential boiler nowhere near that. But, I'm not sure I'm getting
how his indirect tank is plumbed - was it the FEED coming off the
domestic coil, or was it the CIRCULATION?


As for the pressure relief valve. Check your automatic fill valve. It
may need to be replaced. Depending on your water, the valve may be
stuck open a liitle causing your boiler to fill and raise the pressure.

But that is pretty much what would happen with a cracked coil (if the
coil was indeed the domestic feed at domestic pressure), causing
higher pressure water to seep into the boiler thus over-filling it????





Reply to NG only - this e.mail address goes to a kill file.

"3. The installation instructions for the Phase III heater explicitly
specify not to plug the old hot water coil (their exact words:
"Plugging tankless coil inlet and outlet will [sic] result in severe
personal injury, death, or substantial property damage."). Now first,
it seems to me that if the coil is completely purged of water, the only
thing in it will be air, and expanding air won't be enough to rupture
the coil. Additionally, I've seen similar systems in other homes where
the HWC HAD been plugged; also, since our coil is already cracked,
additional damage will be minimal or non-existent. Thoughts? "

If the existing in-boiler hot-water coil resides INSIDE the water in
the boiler, if it leaks it will fill with water. Plugging it in that
case could be bad news.

Leaving it open would mean water would be forced out of it, the rate
depending on the size of the leak.

You could T the 2 ends of the coil together and connect the 3rd leg of
the T to a std pressure relief valve, or you could connect the 3rd side
of the T to one of the boiler-water legs, but it all seems somewhat of
a hack.

If the coil is not submerged in the boiler water, it would seem OK to
plug it (otherwise you'd get fumes through the leak), but I'd seek
professional help considering all the questions involved.

dave