when to turn it on

nicholas bonham-carter

every year at this time, i am always wondering when to start heating the apartments, with our 1-pipe steam system. how do others arrive at this magic date?

i suppose i could look at the 10-day weather for-cast, and when i see projected temperatures lower than a certain degree, then flip the switch.

alternatively, i could let my Honeywell decide. --nbc

crash2009

We have one-pipe steam also.

I live in the same building with the apartments.  I have a tendancy to want to be comfortable.  I usually turn it on, the first night the outside temp is forcasted to drop down to 40 F.  During the day, I shut it off.  On off, on off, most of the month of September.  Near the end of September its on all the time unless we get an unusual heat wave.  If I did not live in the building I would get that outside sensor thing that prevents the boiler from starting unless the temp is a certain degree.     

Brad White

The Magic of the Balance Point

It is amazing how identically appearing homes can hold heat so differently. Obviously differences in insulation and air sealing are at work, but also solar gains and orientation, thermal mass and internal gains, things we all know.



The old "65 degree lock-out rule", probably  will disappear once our housing stock is improved to a reasonable energy standard. Having renovated several homes and living in them on occasion, it was gratifying to see how cold it would be outside before heat was needed, the proverbial balance point.



What skewed the issue was the addition of computers, always on appliances, incandescent bulbs and inefficient refrigerators. Now with LEDs and high efficiency appliances, smart lighting controls, etc. we will see some drop in this free heating, but the tighter homes allow you many good coasting hours!



From my energy audit work, it is abundantly clear that the real savings are in the hours when the outside air temperature is between 30 and 40F in our climate. These are not the coldest hours but there are a lot more of them. Imagine getting your balance point down into that mid 30s range?



For older, uninsulated homes, I would say 65F outdoor temperature (ODT) is fair, but once you insulate, air seal and install good storm windows, if you need heat above 50, something is wrong.



A few years ago I designed the HVAC system for one of our client's homes, a new addition that more than doubled the area. The walls were 2x8 studs filled with Icynene. The roof was similar. Tested separately, the infiltration rate was about 0.25 ACH50 and we had a pair of ERVs in play.



The balance point for this house, well one room in particular, his office, was below freezing because of the computers and such. A north facing room no less. We had installed economizer free cooling, thankfully. The room got to 80F on a 32F day with no heat added, when we discovered that the control system had also locked out the economizer. All of my home design have economizers now.



Sorry to ramble, just some musings.

Mark Eatherton

Interesting musings...

And all that much more need for Smart Home technology.



The days of having one single point of optimum start/stop are long behind us.



Hence the reason why I like variable everything. Houses aren't static things, they are dynamic things, with different exposures, different internal gains, and different occupant needs. So why should our controls be static ON vs. OFF configuration? Our home comfort systems should breath just like the occupants do.



A variable speed circulator, connected to a modulating heat source, connected to modulating non electric TRV's connected to large surface radiant heat emitters equipped for use with very low temperatures is the ultimate in comfort and energy conservation.



With the advent of DCECM blower motors, there really is no reason why we can't have a modulating free air cooling and ventilation system to meet the variable cooling/venting needs of the newer tighter home of today.



The major increases we have seen over the past 10 to 15 years boggles the mind. What REALLY bogles the mind, is where we will be in the next 10 to 15 years.



Boiler? What boiler! I've got a hydrogen fuel cell in my basement that makes heat, electricity and water. It's interfaced with the solar PV/thermal system, which is interfaced with the air/ground source heat pump system, and it is all controlled by the ENV control logic running on my desk top PC.



The future is bright, warm and refreshing :-)



Good stuff on the horizon.



ME

Mark Eatherton

NBC...

Sorry for hijacking/diverting your thread.



The problem with conventional wisdom and applying thermostats in buildings is that the stat is usually placed in the last place that cold creep arrives, that being the core, so consequently, people who reside closer to where the cold creep has arrived start complaining before the thermostat realizes it should be on.



There are solutions, but they have to be thought out completely before employing them.



One thing you could do would be to install a solid state thermostat, like a Tekmar 150 set point controller. Instead of using just one point of sensing, you can wire the sensors in a series parallel configuration and get an average temperature of the critical spaces. This, backed up by the tekmar steam boiler control and a time of day timer would give you the ultimate in temperature/energy control.



My assumption is that you have already deployed non electric TRV's at the radiator vents. A word of caution here. If you have employed TRV's you have to have a "reference" radiator to give up heat when it is being called for or your heating plant will waste energy.



I realize that it is not easy to wire 4 sensors into a finished installation, but it can be done. Use your imagination :-)



ME

crash2009

Let the sensors decide

Sounds like this is something I would like to get.  Let me see if I got this straight.  The Tekmar 150 replaces my current thermostat?  Then I need a Tekmar boiler controller.  And 4 sensors.  The sensors are placed: 1 outside, 1 on the condensate return, and the other 2 within the house (1 in the coldest room and 1 in the warmest)  I think I understand how 3 of the sensors work but what does the temperature of the condensate have to do with it?

Mark Eatherton

The sensor on the condensate return....

Starts the duty cycle based on steam being delivered to the system. It confirms that steam is being condensed in the radiators. Otherwise, if you were only monitoring the presence of steam, you would have a tendency to shut down before the radiators had warmed up.



The four sensors I was relating to are temperature averaging sensors inside the building. Be careful where you plant these sensors because 140 and zero are a 70 degree F average...



The 150 would replace the thermostat currently in the building.



My experience with this type of system is that you do NOT want to have ANYONE controlling the thermostat (i.e. building manager, tenants, owners and so on).



On the shoulder seasons, if residents are feeling chilly, tell them to put on a sweater and feel green :-)



ME

crash2009

OK

So there are 6 sensors?  4 temperature averaging, 1 outside, and 1 on the condensate return.  Plus the Teckmar 150, that need to be wired.  The 150 would use the same wire as the thermostat, Condensate sensor would be easy, Outdoor easy, The control goes on the boiler skin, The averaging sensors could be tricky.  Any recomendation's on averaging locations? 

What do you think NBC?  I know you been thinking about this for awhile. 

 

Mark Eatherton

If memory serves me correctly...

it does require at least one inside air temperature reference sensor, but it has been a while since I've put one in.



As for averaging sensor locations, one on the north, east west and south top floor (worst case loss scenario) situations. Preferrably 1/2 way between the outside wall and the interior hallway wall.



Avoid the usual locations to avoid, like in sunshine, behind doors or near windows.



No easy (wireless) way to run these sensors. Will need to run 18/2 from the averaging sensors to the control location.



ME

Jamie Hall

Good grief...

I still can't program my VCR!



And the place I run is a great draughty old "cottage"... with one thermostat, in the central hall.  Hasn't turned the boiler on yet!

GusHerb

...

I turn the heat on when I can no longer maintain a "comfortable" temperature anymore which for us would be about 70. Or (more so applied to our apartment building) when I see cold enough temps in the forecast that I know it will get too chilly indoors without heat.  If our weather here stays the same way it's going, I'll need to start the boiler in our building in 2 or 3 weeks from now.  

crash2009

Wireless sensors

These guys, R & D Electronics, claim to have wireless sensors.  That might make things easier.  They calculate the duty cycle differently, (no condensate return sensor)   Wireless might make the "sensor balancing" easier.  There would have to be some big fuel savings to make this worthwile.  Honestly, all I really wanted was a simple outdoor reset, so I wouldn't have to hit the switch on and off.  

http://www.rdcontrolsystems.com/index.php