|
Posted by Mark on May 19, 2008, 12:22 pm
> Why =A0not =A0feed the hot water =A0from the =A0electric hot water
> heater into the boiler. A drop in water temperature would
> indicate =A0a =A0need for boiler =A0heat and a rise in temperature
> would =A0shut the =A0boiler down and supply =A0hot water from
> the electric water heater.
> So in summer or at low load the electric =A0hot water heater
> would =A0maintain =A0the =A0temperature and =A0lock the boiler out.
> At high load the electric hot water heater would be unable
> to maintain the temperature and the boiler would start.
>
>
>
>
>
> > Hi, my house currently has a DHW coil sitting in a relatively OK oil
> > boiler (Burnham RSA 110). =A0I put a Hobbs meter on the boiler, and find=
> > that the thing is blowing somewhere around almost 3/4 gal of oil up the
> > chimney in standby losses per day -- that is just the standby usage with=
> > no DHW or heating load, just to sit there. =A0That is with the Aquastat =
set
> > to 125 for the low setpoint, which is about as cool as I want to get it
> > since I like my water to the washer, dishwasher, etc at least that hot.
>
> > So I am thinking about putting in a 50 gal high-efficiency electric hot
> > water heater to augment it, so that I can turn the boiler off when the
> > domestic heat is not needed, e.g. over the summer. =A0I understand other=
s
> > have done this, and have done quite alright saving money with a manual
> > switch-over, so that their DHW is electric during the warm months and th=
e
> > oil boiler is "off" during the summer months.
>
> > However, being a bit of an engineer, I want to complicate this setup --
> > can anyone give me advice or gotchas on my plans?
>
> > - Electric HW heater is on full-time.
> > - DHW comes from either electric, or boiler, and is switched by a zone
> > valve, e.g. like a Taco 3-way.
> > - A second Aquastat / temp switch installed on the boiler flips the zone=
> > valve to draw hot water from the boiler whenever the boiler temp is over=
a
> > certain setpoint, say 120F.
> > - A timer is rigged into the boiler Aquastat, so that the boiler is
> > normally off (full cold), but goes on to the lower setpoint (~130F) when=
> > the timer is on -- this would be for anticipated high hot-water demand
> > days / times, I am thinking 2x / week when a lot of laundry is done. The=
> > boiler is also on to the higher setpoint (~180F) whenever there is a cal=
l
> > for domestic heating, (of course).
>
> > My aim is to utilize the lower fuel costs of the oil boiler when the thi=
ng
> > is hot anyways due to a domestic heat call, or at certain limited times =
of
> > the week when it switches on in order to supply a heavy hot-water demand=
> > (and economize the fuel cost). =A0The aim is to keep the boiler cool, an=
d
> > supply hot water from the electric tank, at all other times.
>
> > Kind of different, does anyone see any gotchas?
>
> > And two more questions along this thread, if anyone has any advice.
> > - Where can I get an idea of anticpated future electric costs -- I am in=
> > CT, and pay $0.16 / KWH which is kind of high -- but the price has not
> > escalated to the rate that oil, gasoline, etc. have in the last 4-6
> > months.
> > - Where can I get some info on the standby heat loss from an electic hot=
> > water heater -- I don't see much on the manuf websites.
>
> > Thanks much for any advice!!!
> > T- Hide quoted text -
>
> - Show quoted text -
ask the electric company about "off peak" metering
Mark
| 
Yahoo! 
Google 
Windows Live 
del.icio.us 
digg 
Netscape 
XML Sitemap