DIY success- cybernetic heater control

[JohnRoberts]

> heater shaking and making a rattling noise as the wires vibrated from first heating up.
>  I decided to try duty cycling

I must re-endorse the Honeywell cyber-thermostat.

Especially for older electric baseboard which creaks.

...as it gets close to set point, then cycles, it runs the heater at part-power.

Oh.... and I'm running 240V baseboard at 120V. 4 feet of baseboard costs a lot more than you paid, and at 120V outputs a lot less, so may not be for you.

I'm uncertain of your fan hack. Seems if the triac sticks ON, it starts to go the full 1500 Watts, it needs "full fan" to stay safe.

I still have the old in wall resistance heat that works, I just don't like the crude mechanical thermostat. The in wall heater made noise too. If I were to get more sophisticated I might attach a real TOD thermostat to the in-wall unit. I wouldn't want to make a permanent hack that the next owner can't just unplug.

Re: my fan hack, it starts at 1/5 power so I am pretty confident it will run at full power, "and" it looks like there is a thermal fuse on the top of the heater stack, probably a simple temperature sensitive link that physically opens up if the temperature gets high enough, "and" there is also the front panel bimetallic thermostat that even when turned full up, like I have it now, will probably open before 451'F. 

[edit] The fan is a cheap POS working in a difficult environment. I expect the fan to be one of the weaker links and not to last as long as the rest of the heater. The thermostat control is sensing temperature inside the heater chassis, so loss of the fan will likely just reduce the amount of heat delivered to the room and not cause catastrophic overheating. If when the fan fails or gets noisy I may just disable it. [/edit] 

The tilt switch is cleverly built into the thermostat bi-metallic contact assembly so when tilted it opens the thermostat.

This heater is about a hundred times safer than my old one, ignoring the extra heat output. It even has a high/low switch where one heat coil gets shorted out for max heat... I have it set low but still 2x the power of my old one. 

JR

PS, My next project is an indoor storm window design that can reduce a major source of heat loss.  More about that later.

 

[PRR]

> a real TOD thermostat to the in-wall unit. I wouldn't want to make a permanent hack that the next owner can't just unplug.

I still like that Honeywell. From your POV: it looks decent when you shop to the next owner, any electrician can put the dumb 'stat back, *and* the modulated power minimizes hot/cold creaking.

Problems:

It leaves nothing for you to do

The interface sucks. The display is small and not back-lit. The buttons are smaller. I'd say it is for young people, but they expect an iPhone-app interface. And IMHO a *flaw*... if you fail to set a time-period, it may default to "max". Or that's how it seems to me. Each weekend I'd find it running HOT, well above any set-temp I would have put in. I went through the *whole* 4/day M-F & SS sequence, and then it was fine.

Line-power wall thermostats can be 1-pole or 2-pole. The unit I got is 1-pole. I don't recall if they make a 2-pole model. Obviously the heater "can" be wired so a 1-pole suffices. 2-pole may be about safety, or maybe about load-balance? See what you got. (I suspect 1-pole.)

 

[JohnRoberts]

> a real TOD thermostat to the in-wall unit. I wouldn't want to make a permanent hack that the next owner can't just unplug.

I still like that Honeywell. From your POV: it looks decent when you shop to the next owner, any electrician can put the dumb 'stat back, *and* the modulated power minimizes hot/cold creaking.

Problems:

It leaves nothing for you to do

The interface sucks. The display is small and not back-lit. The buttons are smaller. I'd say it is for young people, but they expect an iPhone-app interface. And IMHO a *flaw*... if you fail to set a time-period, it may default to "max". Or that's how it seems to me. Each weekend I'd find it running HOT, well above any set-temp I would have put in. I went through the *whole* 4/day M-F & SS sequence, and then it was fine.

Line-power wall thermostats can be 1-pole or 2-pole. The unit I got is 1-pole. I don't recall if they make a 2-pole model. Obviously the heater "can" be wired so a 1-pole suffices. 2-pole may be about safety, or maybe about load-balance? See what you got. (I suspect 1-pole.)

Yes, that honeywell looks like a nice unit and appears capable of managing my old in wall heat unit (up to 3kW @ 240V).  Modern units from the same company look different but are only 1000W so the Honeywell should manage.

I am curious about how it manages close to temperature. I really like my 20-40-60-80-100% duty cycle depending on how close.  I also sync to zero crossings, while i guess they could use a glorified light dimmer circuit. I was worried about EMI and or spikes.

I am not enthusiastic about hacking into my 240V heater wiring, or paying somebody to, but that would be the classy fix... I have a few rooms with sticky thermostat controls. They stick off, not on... probably just dirty.

If this (Honeywell) was easy I could wire up several rooms with real thermostats, while I have a few rooms I never heat. In fact I swapped out a heater with good thermostat for the main room heater where I did use the heater, before I bought the heat pump/air co...

These days I am not using any of the old in-wall heaters, and turn off the heat pump at night.

JR

PS: There is a new product from some silicon valley nerds, that has all the iphone hooks and smart features like knowing when you are in the room, learning your patterns etc.

 

 

[PRR]

> hacking into my 240V heater wiring, or paying somebody

It's just two wires, same as the old switch. Doesn't even take the other side of the line; it steals power with a small voltage drop (on) or leakage current (off). That's why it must feed at least a 2 Amp load, any less starves it. (My "240V 1000W" working 120V 250W seems to be on-the-edge.)

Manual

It holds through short power failures, like the two times this year when I did a whole-house shut-down for feeder work, or last year's pop-out at the distribution yard. 5 hours will lose the clock.

I can't find a good blurb about the proportional operation. One comment says "15 seconds" but that's a reviewer so probably clueless. I have not heard any RFI, but I don't have much RFI-sensitive stuff any more. I'd assume zero-crossing just because it is easier on the Triac and doesn't cost anything these days.

The heat-pump is a better plan for whole-house. When ready to sell, you want a "working" thermostat in each room so the Buyer's Inspector has something to play with, but the mechanical jobs are far cheaper ($25 instead of $50). But for a single bedroom when not cold enough to run the pump all night, a bit of electric fire takes the edge off, and a ToD controller gets ready for bedtime and remembers to shut-off in the morning.

 

[JohnRoberts]

> hacking into my 240V heater wiring, or paying somebody

It's just two wires, same as the old switch. Doesn't even take the other side of the line; it steals power with a small voltage drop (on) or leakage current (off). That's why it must feed at least a 2 Amp load, any less starves it. (My "240V 1000W" working 120V 250W seems to be on-the-edge.)

Not exactly the same, the old mechanical thermostat is built into... the front of the heater

I'll need to cut a hole in my wall to mount a junction box, then break the 240V feed to heater. The instructions you posted say to mount the thermostat on an opposite wall from the heater. That isn't going to happen.  We'll see

Manual

It holds through short power failures, like the two times this year when I did a whole-house shut-down for feeder work, or last year's pop-out at the distribution yard. 5 hours will lose the clock.

I can't find a good blurb about the proportional operation. One comment says "15 seconds" but that's a reviewer so probably clueless. I have not heard any RFI, but I don't have much RFI-sensitive stuff any more. I'd assume zero-crossing just because it is easier on the Triac and doesn't cost anything these days.

We finally had some 20' temps last night and my bedroom remained cozy, and heater is still quiet enough that I never hear it working any more. I didn't see it running at more than 40% to maintain temp, when I checked (I can tell from how bright the front panel lamp is).  I did notice that the proportional heat as I approach threshold wasn't strong enough to actually reach target when very cold outside. This is expected and it maintains temperature at around 1' low, when really cold. I can tweak this so it regulates tighter but it's not a big deal. It delivers much better temp regulation than old in-wall heater thermostat, that would heat the room too warm in warm weather, and not warm enough in cold weather. 

The heat-pump is a better plan for whole-house. When ready to sell, you want a "working" thermostat in each room so the Buyer's Inspector has something to play with, but the mechanical jobs are far cheaper ($25 instead of $50). But for a single bedroom when not cold enough to run the pump all night, a bit of electric fire takes the edge off, and a ToD controller gets ready for bedtime and remembers to shut-off in the morning.

I have considered going crazy and burying a ground based heat pump line, but my money now is probably better spent on reducing the heat loss from windows and attic. I need to grab the low hanging fruit first.

JR

 

[PRR]

> thermostat is built into... the front of the heater

Ah, OK. Some of those are j-box stats mounted in the heater, but probably only a knob-hole through the panel. Aside from major metal-work, you could NOT decently operate the digi-stat at the floor. Extending wires up the wall puts the stat in a bad place (worse than in front of the heater where it gets mostly return air).

Yes, windows and usually attic first. (My garage loft has R-40 overhead and R-1 in the floor so I'm topsy-turvy; but the floor will be easy to stuff when we decide to heat that space.)
__________________________

A different cyber-controller question: is there an easy-to-use opto-triac fat enough to switch basement lights? (Presently 3 Amps but the nature of the thing suggests 15A-20A Incandescent rating.) Cheap? Or is this still a relay world?

EDIT-- Sharp S116S02 Series is nom 16A and has "Zero crossing functionary" for $6.

 

[JohnRoberts]

I rolled my own from two separate parts. First an old school snubber less 16A 800V triac T1635T, with that gate connected to a small opto-triac (TLP160G). The opto is only 70mA continuous output but 2A peak so capable of firing even a balky traic while letting me drive it well isolated from the mains (2500V) with a few mA of LED current. I put a small R in series with power triac gate but don't recall the value.

There may be a cheaper better way for large scale production but my one off opto triac was $0.80, and power triac <$3 in small quantity.  Perhaps not optimal for wiring into a junction box, the opto was SMD.

JR

 

[JohnRoberts]

I finished my first round of redneck storm windows. The plan changed a little as plans do when they meet reality.  I ended ip with is some 3/4" x 1 1/2"  pine strips since I couldn't find the 1/2 Square stock I was looking for. The wood screw I ordered were too short for the wood i got but I improvised.

The big window is roughly 4'x8' so the frame was a little fragile, I ended up adding corner braces. I found some self adhesive extruded foam to make an air tight seal around the periphery. I stapled drop cloth plastic to both sides of the frame capturing a 3/4" pocket of air to serve as an insulator. So when wedged into the inner window sill, I now have captured a pocket of air between the outside window glass and the red neck storm window, then another pocket of air, inside the storm window. So two separate air tight pockets.

I expect there to be a significant difference in heat loss vs. a single layer of a glass, vs, two captured pockets of still air. Note: I shill have curtains I close at night that add yet another pocket of still air, while not air tight so some convective flow. 

It works, the air tempertur outside is now up in the '70s compared to 40's last week..  ;D ;D (kidding).

A made a similar but much smaller version for the window over my sink, so the large room, living area should now be a little easier to heat, when the temps drop again later this week. 

JR

edit/ I have discovered some engineered films for transparency. Some block UV  and attach to the glass and are pretty thin. So far they look pretty expensive but being transparent would be nice.  /edit.

 

[PRR]

> It works, the air temperture outside is now up in the '70s compared to 40's last week..

This is a very real effect. I spent months ditching my wet acre. Hasn't rained since.

Golly, I can't remember the last single-glass window I saw (other than garage and chicken-shack).

 

[JohnRoberts]

> It works, the air temperture outside is now up in the '70s compared to 40's last week..

This is a very real effect. I spent months ditching my wet acre. Hasn't rained since.

It rained here last night...  It didn't stop raining very long after I dug my 100' long ditch (by hand) and buried a 4" drain pipe to drain my back rain ditch into my front rain ditch that pulls down lower.  My latest rain ditch improvement project is to fill in my far back rain ditch that the town dug far too deep some 10 years ago. Since there was often flooding on that end of town, I guess the town brain trust figured deeper ditches would hold more water. Problem is they hold water for a week and more after it rains, breeding mosquitos. When the state recently cleaned out 20 years of sediment from my front rain ditch on a state hwy, graded properly.  I had them leave the removed dirt and sod behind, so I have been moving my ex-front rain ditch dirt, to my far back ditch one wheelbarrow at a time.  It is helping but after a couple months of weekends I still have more to do. The standing water in my back ditch is now only about 1-2" deep, so dries out in a day or two without rain. I am nowhere near running out of front ditch dirt.   

Golly, I can't remember the last single-glass window I saw (other than garage and chicken-shack).

Welcome to my world.  ;D Probably a deep south/cheap construction thing. Rather than the slide in outer screens, that would get replaced with slide in glass storm windows for the winter, I have permanent screens that do not come out. I even recall the old school storm windows from when I was kid, that hung from hooks near the top of the window frame. Up north storm windows to keep in heat are a necessity not luxury. 

I can understand how southern luxury used to be an attic fan that would pull hot air out of the house when it was cooler outside at night. In almost 30 years I've used that attic fan a handful of times. These days of air conditioning, permanent glass storm windows would be nice, but not a practical option for me (the screens do not come out). 

I am balking at the cost of proper window film, that mainly appears engineered to stick to existing glass. They say that some of these should not be used on inside of double pane , because the heat buildup inside could cause the windows to crack. That's interesting for summer relief. 

So my red-neck storm windows appear like they will be effective at keeping heat in/or out, but the cheap drop cloth plastic is not very transparent (especially going through two layers of it). The good window film only blocks around 10-11% of the light, so two layers of it around 80%.  Hmmmm I may do a couple small windows with fancy film to see how it works. Don't think I can afford the 4'x8' big window. I could just about fit a piece of real glass on the inside of the window extrusion. More to think about. 

JR

 

[PRR]

> figured deeper ditches would hold more water.

Well, no they don't (not much), tho I admit it took a while for me to learn.

You can hold a sprinkle in a basin or ditch. When it RAINS, there's no ditch big enough. Short of Massive Construction, such as Oregon flood-plain agriculture, or the acres of basin behind modern shopping malls.

> they hold water for a week and more after it rains, breeding mosquitos.

That too. Or in my pocky soil. Specially after they built-up the driveway, built-up the roadway, over ledge, which dammed uphill water on my front acre. 80% of the year it was 5-foot islands in shallow lake which didn't drain. Actually no good for breeding our state bird (the Black Fly needs slow current) but mosquito larva loved it.

The road-ditch, which didn't drain my land, silts-up enough to hold an inch which supports an algae-bloom which then dies and stinks bad. I dug that out once but I think I need to dig again. (Anyway the work is good for my back.)

 

[PRR]

> cheap drop cloth plastic is not very transparent

I've used a 3M window film which sticks to your trim and leaves an air-space, is pretty clear.

Home Depot doesn't have it (or Search can't find it).

http://www.homedepot.com/s/3m%2520window?NCNI-5

I assume the Frost King stuffs are semi-comparable. However the Reviews are mixed. And the listings don't *clearly* say how much they cover. Prices low enough to try, and hope for payback.

Nine 62"x42" for $14, 3.5 stars:

http://www.homedepot.com/p/Frost-King-E-O-Indoor-Window-Insulation-Kit-9-Pack-V73-9QPA/202262335#.UorRCydGZwY

> afford the 4'x8' big window.

There's 84 in. x 110 in for 8 bucks, four stars.

http://www.homedepot.com/p/Frost-King-E-O-84-in-x-110-in-Patio-Shrink-Window-Insulation-Kit-V76QPD/202262330#.UorRFSdGZwY

As many reviews say, the sticky-tape either does not stick, or leaves goo or pulls paint (or all three). Your sticks are probably a better idea.

 

[JohnRoberts]

Yup I found a roll of shrink window film at Mcmaster carr., ordered some earlier this week.  Another Ah-hah moment I had is that I don't need to make my entire 4'x 8' red neck storm window transparent. I just need a middle section that I can see through. The shrink film was a little misleading when I first saw it, but it doesn't have to be shrunk. Obviously this is not a unique situation. Apparently I am not the only red neck.  ;D

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DON'T TRY THIS AT HOME.

Sure enough after about two weeks, even with the dropping resistor, the fan noise became too much for my pursuit of noiseless heat to tolerate. So I looked into running my $19 heater fan less. As PRR speculated at full grunt without a fan the internal heat rise is too much. There is temp cut out in series with heater elements, with this bypassed the top of the metal heater gets well above the UL 100'C or so limit consider safe. Since the heater is designed for heat to get blown out the front, I looked into tilting it back so convection could be more effective at removing heat from inside. This helped some (after I defeated the tilt switch), but now the heat elements, relatively quiet when vertical  were noisy horizontally (?). And the front panel thermostat, now on the top surface was getting too much heat so the heater would cycle off and could not keep up with the 30' outdoor temps. With the heater oriented vertically, with the temp cut out defeated it was making some serious heat, while way too hot to touch. Without a fan the heating elements were red hot, twisting and distorting. The cheap vinyl insulation on the wiring inside melted. The heating coils look like a slinky toy that lost a fight. After running at full snot vertically, there was  a momentary flash of white light and I quickly unplugged it. After shifting back to my old school fan less heater, I noticed that it wasn't turning off above target temperature. So apparently the power triac failed short circuit.

I just replaced the (16A 800V) triac and I'm back in business with my old small fan less heater. The opto logic drive triac was OK. I added some more heatsink to the power triac but I suspect it took a very large current transient, momentarily.

The wisdom of buying a quiet baseboard unit is making more sense.  i can get close to my original 650W from 120V from an oversized 240V unit. If I ever decide to go legit and wire this for 240V with a real thermostat it will even be acceptable to normal people with more than enough heat output. Unfortunately the baseboard heaters are all designed for 240V so the cheap ones make too little heat output from 120V.

JR

[edit- my window shrink film just came in... this stuff looks like saran wrap, just wider, and more expensive. As long as it stops the breeze it should work /edit]

 

[PRR]

> original 650W from 120V

240V resistors run at 120V give 1/4 power (I don't see a large tempco in mine).

So you want 4*650W = 2,600W.

Permanent-type baseboard is *usually* 250 Watts (800BTU) per foot.

So you want 10 feet of baseboard. A LOT for a bedroom.

Running "1000W" (as 250W) in a very small space, I also feel the need for some fan-blow to break-up stratification. However a 12V PC fan on 9V gave too much draft, kinked my back. I should fool with a much larger (like 9") fan with massive dropping resistor. Probably have to wash the bearings and oil with the thinnest stuff I can find (maybe ATF).

 

[JohnRoberts]

There are two baseboard candidates at Lowes, for $60- $75 that will get me in the 500W@120V range.

I don't feel like I need a fan for that much power spread across several feet of baseboard. I could add a fan but don't feel like I need it. The actual temp thermostat is so much better than the crude mechanical thermostat on the old in wall heater that I am very happy with the room temp control.

I tweaked the duty cycle again to increase the frequency of the PWM period.. Still switching at zero crossings. Before i was using x/5 half cycles. Now I am using x /3 half cycles so I get 1/3 and 2/3 power but with less LF vibration.  The old heater is behaving and nice and quiet especially at 1/3 power.

JR

 

[JohnRoberts]

Last night when I did my weekly shopping I looked for a large enough base board unit to get close to 500W at 120V. The largest they had on display was 1500W at 240 so only 375W and not cheap.

So after thinking about it overnight I considered buying  2x 1000W at 240V to use in parallel to make 500W now , and then later heat two rooms from 240V when wired in permanently to 240v. However I don't need to heat two rooms, just my bedroom quietly.

When I went on the WWW to look at cheap 1000W units, I found this
http://www.lowes.com/pd_403053-1509-4F1000-1W_0__?Ntt=%3A+4f1000-1w&UserSearch=%3A+4f1000-1w&productId=3691066&rpp=32

1000W @ 120V....  So I'm glad they didn't have the big 240V unit in stock last night.

JR

 

[JohnRoberts]

As chance would have it, the 1kW baseboard heater element I ordered over a week ago arrived today, along with 70' outside temps.  I was really looking for it last week when we had overnight temps in the 20's but that how it goes.

Long story short, this heater runs dead silent...  ;D ;D ;D So the only way I know when it is on is from the controller LEDs (and heat output.) I am looking forward to silent night time running, in the short term there is some new heater smell, but that too will pass.

My old 850W aux unit was not enough power to keep the room toasty with 45-50' inside/outside differential, The 1kW will buy me a few more degrees (6' by my back of the envelope calc). The good news is <20' is not that normal for down here, and if the bedroom temp dips a few degrees in the middle of the night while I'm under the covers so what...

So success...  Now all I have to do is fine tune the time constants... I have pushed it out to 16 second sample/adjust interval. Too short and it overshoots and undershoots. So longer time constants with plenty of anticipation to slow it down when approaching temp targets seems to work. 

JR