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Boiler Basics - Part III - External Components

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00:00:11.420 00:00:11.430 00:00:28.460 00:00:28.470 welcome to WX TV your online source for
00:00:31.740 00:00:31.750 weatherization training this is part
00:00:34.140 00:00:34.150 three of our boiler basics series and in
00:00:36.750 00:00:36.760 this last segment Mike is going to break
00:00:38.910 00:00:38.920 down the external components of a boiler
00:00:41.130 00:00:41.140 system and how they function okay at
00:00:49.049 00:00:49.059 this point I think it's important to
00:00:50.549 00:00:50.559 explain the external components of a
00:00:53.100 00:00:53.110 boiler I try to split a boiler up into
00:00:55.500 00:00:55.510 two parts I the boiler is it is itself
00:00:58.470 00:00:58.480 it has its own things that you need to
00:01:00.810 00:01:00.820 worry about and then you have everything
00:01:03.150 00:01:03.160 external to the boiler and depending on
00:01:06.450 00:01:06.460 the type of heating system you can have
00:01:08.040 00:01:08.050 a whole bunch of bells and whistles here
00:01:09.780 00:01:09.790 this is a pretty simple system it's a
00:01:12.300 00:01:12.310 two zone baseboard heating system here's
00:01:16.200 00:01:16.210 one of those own valves and here's the
00:01:17.670 00:01:17.680 other zone valve and you can get into
00:01:19.950 00:01:19.960 systems that have and it's one
00:01:21.690 00:01:21.700 temperature whatever temperature the
00:01:24.240 00:01:24.250 boiler runs that's what temperature we
00:01:26.310 00:01:26.320 send the way this system can't runs our
00:01:30.330 00:01:30.340 returned water is coming here down each
00:01:34.290 00:01:34.300 one of these through this pipe down down
00:01:38.850 00:01:38.860 this pipe through the back into the
00:01:41.999 00:01:42.009 bottom of the pump the pump is right
00:01:43.559 00:01:43.569 here so the pump is pulling here and
00:01:47.449 00:01:47.459 then the pump pushes water into the
00:01:51.270 00:01:51.280 boiler it gets heated up then the hot
00:01:54.660 00:01:54.670 water comes out of the boiler up through
00:01:58.620 00:01:58.630 here through this this is an air scoop
00:02:02.850 00:02:02.860 and out to the zones we have two zone
00:02:08.040 00:02:08.050 valves that's that means there's a
00:02:09.900 00:02:09.910 thermostat that runs this so envolve and
00:02:12.150 00:02:12.160 there's a thermostat that runs this zone
00:02:13.949 00:02:13.959 valve both zones could be calling at the
00:02:15.990 00:02:16.000 same time all that means is that both of
00:02:17.730 00:02:17.740 these valves are open the pump now will
00:02:20.100 00:02:20.110 pump some water through this zone and
00:02:22.170 00:02:22.180 some water through this zone they're in
00:02:24.030 00:02:24.040 pair piped in parallel or one zone could
00:02:26.460 00:02:26.470 be column just one and the water is
00:02:29.100 00:02:29.110 being piped pumped through that one zone
00:02:31.949 00:02:31.959 if you have a mechanical thermostat you
00:02:34.320 00:02:34.330 set the heat anticipator on the
00:02:36.870 00:02:36.880 mechanical thermostat
00:02:38.640 00:02:38.650 to the amperage draw of the zone valve
00:02:40.830 00:02:40.840 on a forced air furnace you typically
00:02:44.160 00:02:44.170 set it to the amp draw of the gas valve
00:02:46.319 00:02:46.329 that's one of the differences with multi
00:02:49.319 00:02:49.329 zone pieces of equipment is you set it
00:02:52.080 00:02:52.090 to whatever device the thermostat is
00:02:55.710 00:02:55.720 controlling in this case the thermostat
00:02:57.990 00:02:58.000 controls the zone valve it allows the
00:03:01.080 00:03:01.090 motor in the zone both to open the valve
00:03:02.970 00:03:02.980 in this house we have digital
00:03:06.179 00:03:06.189 thermostats so we don't even need to set
00:03:08.280 00:03:08.290 the heat anticipator okay this is our
00:03:10.440 00:03:10.450 air scoop and this is an auto air vent
00:03:12.949 00:03:12.959 basically what this does is it removes
00:03:15.690 00:03:15.700 any oxygen that is in the heating system
00:03:19.830 00:03:19.840 we want to get rid of all the oxygen
00:03:21.690 00:03:21.700 because number one oxygen helps keeps
00:03:24.619 00:03:24.629 rust from forming what we really want is
00:03:28.500 00:03:28.510 a dead water in here with no air pockets
00:03:30.500 00:03:30.510 so as the air moves across here there's
00:03:34.440 00:03:34.450 a little scoop any bubbles that are
00:03:36.869 00:03:36.879 writing on top get scooped up and pushed
00:03:38.819 00:03:38.829 up to the top this has a float in it
00:03:41.539 00:03:41.549 when it's full of air the float drops
00:03:44.699 00:03:44.709 and allows air to come out of this part
00:03:48.539 00:03:48.549 port right here so it's critical that
00:03:50.759 00:03:50.769 these little caps are loose you don't
00:03:54.509 00:03:54.519 want them tight because if they're tight
00:03:56.069 00:03:56.079 then it shuts that off and the air can't
00:03:59.309 00:03:59.319 it just collects in here and it can't be
00:04:02.039 00:04:02.049 released from the system this component
00:04:04.680 00:04:04.690 over here is the pressure regulator this
00:04:07.439 00:04:07.449 is our house pressure which typically is
00:04:09.360 00:04:09.370 you know 60 75 psi on this side it
00:04:14.250 00:04:14.260 reduces the pressure over to this side
00:04:16.469 00:04:16.479 to 12 psi so anytime the water pressure
00:04:19.560 00:04:19.570 drops below 12 psi on this side this
00:04:22.980 00:04:22.990 automatically adds some water this is a
00:04:25.710 00:04:25.720 closed system so it really is a rare
00:04:28.200 00:04:28.210 occurrence when that does happen you
00:04:31.260 00:04:31.270 don't want to add a lot of water to a
00:04:33.629 00:04:33.639 system you want it to you want to look
00:04:36.839 00:04:36.849 for leaks and fix leaks raw water is
00:04:39.960 00:04:39.970 hard on a system you want to get the
00:04:43.050 00:04:43.060 water in one time and minimal water
00:04:45.659 00:04:45.669 being added one thing that this doesn't
00:04:47.820 00:04:47.830 have is a backflow preventer that would
00:04:50.219 00:04:50.229 prevent any water from
00:04:52.110 00:04:52.120 actually going from here into the
00:04:54.300 00:04:54.310 drinking water of the house depending on
00:04:57.510 00:04:57.520 where what your codes are where you're
00:04:59.219 00:04:59.229 located in this particular case this
00:05:02.580 00:05:02.590 home owners on a well and when you're on
00:05:06.659 00:05:06.669 a well you don't have to have as in this
00:05:09.330 00:05:09.340 area as stringent of a backflow
00:05:11.340 00:05:11.350 prevention at the minimum this would
00:05:13.890 00:05:13.900 take a Watts 9 d backflow preventor a
00:05:16.710 00:05:16.720 lot of employment places would require a
00:05:20.129 00:05:20.139 reduced pressure backflow preventor but
00:05:24.719 00:05:24.729 it really should have a backflow
00:05:26.790 00:05:26.800 preventor of some sort
00:05:28.080 00:05:28.090 the next piece we want to look at is
00:05:29.730 00:05:29.740 this expansion think this is one of the
00:05:31.920 00:05:31.930 most overlooked pieces on a heating
00:05:36.029 00:05:36.039 system if you take a look at here this
00:05:38.550 00:05:38.560 kind of this little diagram right here
00:05:41.629 00:05:41.639 kind of gives you an idea of what it is
00:05:44.189 00:05:44.199 inside on one side of the bladder is
00:05:47.210 00:05:47.220 water and on the other side of the
00:05:49.920 00:05:49.930 bladder is air so we have this rubber
00:05:53.580 00:05:53.590 bladder that separates the two well what
00:05:57.510 00:05:57.520 this does is it absorbs pressure that is
00:06:00.060 00:06:00.070 created when we heat up water when we
00:06:02.310 00:06:02.320 heat up water it expands and water is
00:06:05.879 00:06:05.889 non compressible so it can get to very
00:06:08.100 00:06:08.110 high pressures so what this does is it
00:06:10.469 00:06:10.479 absorbs the pressure that's generated as
00:06:12.540 00:06:12.550 the water heats up so as we heat water
00:06:16.080 00:06:16.090 up it has a place to go which keeps the
00:06:19.980 00:06:19.990 pressure in the system pretty consistent
00:06:22.020 00:06:22.030 this particular expansion tank is
00:06:27.029 00:06:27.039 pre-charged to twelve psi which means we
00:06:30.089 00:06:30.099 would also want our pressure regulator
00:06:34.200 00:06:34.210 at 12 psi so everything starts at 12 psi
00:06:38.040 00:06:38.050 and then we heat water up the as it
00:06:40.890 00:06:40.900 expands this absorb some of that
00:06:42.570 00:06:42.580 expansion one of the ways we test this
00:06:47.400 00:06:47.410 is on the bottom there's an air air
00:06:51.240 00:06:51.250 shree a Schrader valve where you can add
00:06:55.040 00:06:55.050 air to the system okay it looks like the
00:06:59.820 00:06:59.830 valve on a bicycle tire and what I do is
00:07:04.529 00:07:04.539 I just barely
00:07:05.760 00:07:05.770 hit this and if water comes out of it
00:07:08.760 00:07:08.770 then that tells me that the bladder has
00:07:11.129 00:07:11.139 a hole in it I can also tap on it
00:07:14.070 00:07:14.080 sometimes until I have a hollow sound
00:07:18.089 00:07:18.099 here of a water sound here but really
00:07:22.290 00:07:22.300 the sure way is to just tap this thing
00:07:24.420 00:07:24.430 and I got air I didn't get water that
00:07:27.600 00:07:27.610 tells me that the bladders doesn't have
00:07:31.140 00:07:31.150 a hole in it if the bladder gets a hole
00:07:34.080 00:07:34.090 in it then this thing fills up with
00:07:35.339 00:07:35.349 water this thing adds water till
00:07:37.980 00:07:37.990 everything's full and what happens is
00:07:40.860 00:07:40.870 the the boiler fires up it heats up the
00:07:44.129 00:07:44.139 water expands and it has no place to go
00:07:46.309 00:07:46.319 because this water is heated as well and
00:07:49.070 00:07:49.080 what happens is the pressure starts to
00:07:51.570 00:07:51.580 climb it climbs above 30 psi and then we
00:07:54.659 00:07:54.669 start losing water out of our pressure
00:07:56.399 00:07:56.409 relief out okay and once we get around
00:08:01.020 00:08:01.030 30 water starts going out of that and
00:08:02.879 00:08:02.889 it's a chain reaction then we add more
00:08:05.219 00:08:05.229 water when it shuts down and cools off
00:08:07.339 00:08:07.349 it heats up it gets to a high pressure
00:08:10.860 00:08:10.870 and we just keep running new raw water
00:08:14.129 00:08:14.139 through this over and over and in this
00:08:17.070 00:08:17.080 case the the drain for the relief valve
00:08:19.920 00:08:19.930 is down in the crawlspace so you really
00:08:23.100 00:08:23.110 wouldn't know if it was occurring it
00:08:26.550 00:08:26.560 would be nice if the if the drain for
00:08:29.640 00:08:29.650 the relief I went into a pan and then
00:08:31.560 00:08:31.570 you could see when that happens that
00:08:36.420 00:08:36.430 that would be a better way of having it
00:08:38.790 00:08:38.800 than the way it is another thing I ran
00:08:41.790 00:08:41.800 into is when you buy one of these
00:08:47.000 00:08:47.010 pressure tanks when they're pressurized
00:08:51.710 00:08:51.720 if and I've seen this on certain model
00:08:56.190 00:08:56.200 numbers not necessarily the model 30 but
00:08:59.579 00:08:59.589 different model numbers they may be they
00:09:02.490 00:09:02.500 pressurize them to 12 psi at sea level
00:09:04.740 00:09:04.750 and then you bring them up to a high
00:09:07.230 00:09:07.240 elevation like this like 5000 feet
00:09:11.370 00:09:11.380 elevation well what happens is that
00:09:14.220 00:09:14.230 pressure is no longer 12 psi it's a
00:09:16.470 00:09:16.480 higher pressure and so then you just
00:09:19.440 00:09:19.450 if you don't even check it before you
00:09:20.880 00:09:20.890 install this and you just install it
00:09:22.710 00:09:22.720 assuming that that's correct now you
00:09:25.470 00:09:25.480 have a higher pressure expansion tank
00:09:28.470 00:09:28.480 and what happens is because of that high
00:09:31.980 00:09:31.990 pressure it can absorb as much expansion
00:09:36.450 00:09:36.460 and that may cause you to lose water out
00:09:39.360 00:09:39.370 of your relief valve your pressure might
00:09:40.980 00:09:40.990 get too high so it's critical to check
00:09:43.290 00:09:43.300 the pressure on these before you install
00:09:45.060 00:09:45.070 them the other trick is is you cannot
00:09:48.210 00:09:48.220 check the pressure on these reliably
00:09:51.750 00:09:51.760 when the system is pressurized you need
00:09:54.720 00:09:54.730 to check it when it's not pressurized so
00:09:57.450 00:09:57.460 in order for me to set the pressure for
00:09:59.400 00:09:59.410 this I need to relieve the pressure on
00:10:01.950 00:10:01.960 the boiler get it down to zero I take my
00:10:05.310 00:10:05.320 just like a tire gauge put it on here
00:10:07.860 00:10:07.870 and I check my pressure if I'm below 12
00:10:10.800 00:10:10.810 psi then I add a little bit of air to
00:10:12.720 00:10:12.730 get it to 12 psi and vice versa if I'm
00:10:15.570 00:10:15.580 above I let a little air out let sit for
00:10:20.010 00:10:20.020 another episode of WX TV in our boiler
00:10:22.920 00:10:22.930 basics series thanks Mike for all that
00:10:25.530 00:10:25.540 information I think there's something
00:10:27.060 00:10:27.070 there for the beginner all the way up to
00:10:29.160 00:10:29.170 the seasoned HVAC technician and thank
00:10:31.620 00:10:31.630 you for watching WX TV your online
00:10:35.010 00:10:35.020 source for weatherization information
00:10:37.740 00:10:37.750 techniques and expert advice
00:10:40.670 00:10:40.680

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