Greetings folks. Yes, I am alive and well and I check in here from time to time, though I have not had much time to post.
I've come to the end of my technical expertise with a refrigerator issue, and I am hoping some of you refrigeration experts here can help me out. If refrigeration compressors are not your thing, the rest of this post will probably make little sense, and you might as well skip it...
The short version is that I bought a brand new, household, 10.3 cubic foot fridge from Lowes (Haier HA10TG30S), and it drags the output of my Magnum MS4024 down from 120vac to ~85vac briefly when the compressor starts. The Magnum is handling everything just fine, but there are a few other things around the house that don't like the momentary drop-out.
I've looked at the circuit diagram on the back of the fridge. It's a pretty standard PSC design, two windings with a run capacitor in series with one of them. What they are doing to start the compressor is simply shorting the run cap with a PTCR, which basically just drops the start winding right onto line voltage until the PTCR heats up. It makes for a cheap design (hey, the whole fridge cost less than $400), but it depends on a basically unlimited power grid behind it to supply the inrush. The output of a 4kW inverter is definitely not unlimited.
Haier won't tell me the value of the run cap, the temperature of the PTCR, or even the HP of the compressor. I think what I need here is to simply add a start cap in series with the PTCR, but I don't know how to figure the proper size and rating of the cap. If I use the existing PTCR, at least I can be reasonably sure that the cap will be out of the circuit in the proper amount of time.
The nameplate wattage of the compressor is 300w, which I would guess to be about a 1/4-horse model.
So my questions are:
1. Can anyone tell me what cap I should use in series with the PTCR (thus parallel with the run cap)?
2. If not, what's the risk in starting out with, say, 70mfd to see if it helps (in series with the existing PTC, which should take it out in plenty of time)?
3. Is there a better way, such as replacing the PTCR with a potential-relay hard start kit?
4. If so, what size kit?
Thanks in advance...
-Sean
who moved from a bus to a boat
(but still has the bus)
Sean-How're Doin? Enjoying your blog about your boating adventures. I realize that you got that refer at a great price. I have changed my refer in the bus to a NovaKool 9000 and really like it. It pulls barely 5amps at 12vdc, uses the Danfoss compressor, and has a separate evaporator for the refer and freezer. Granted they're about 4 times what you payed. Plus they have front air discharge.
My first thought is either a larger capacitor or a separate start capacitor. A/C's have hard start kits-could you use that? I'm sure Nick Badame could answer these questions more intelligently. Good luck, TomC
Tom
I had the same question. Sean for years sang the praise of his 24 volt marine refer and freezer. Seems the best set-up when you have a house batteries already; don't have the power losses through the inverter and you just use the inverter for loads that must be supported on AC. I'm sure Sean had good reasons for going that direction. Sorry I can't help on cap sizing.
Quote from: TomC on July 30, 2014, 09:23:49 AMSean-How're Doin? Enjoying your blog about your boating adventures. I have a NovaKool 9000 and really like it. It pulls barely 5amps at 12vdc, uses the Danfoss compressor, and has a separate evaporator for the refer and freezer. Granted they're about 4 times what you payed. Plus they have front air discharge.
Yeah, nothing to add regarding any knowledge but it is always good to hear from you, Sean. Aside from the fridge issues, I hope that all is going well.
I have a similar Nova-Kool to Tom's - mine is an 8700 (or something like that) so it's slightly smaller but it works like a champ. It seems a little weak in 98º and 98% humidity in North Carolina (I have extra insulation behind the specified air space against the outside wall and it works OK, just seems a little weak) but on most counts I like it. Oh, yeah, the other count I don't like is the $$$$ (ouch!!!). And of course your 10.3 fridge is WAY bigger than the Nova-Kool. Good luck on what it takes to make it work right. Too bad that Haier's customer service (?) is as bad as we can expect from many companies these days.
Thanks, guys.
To answer the question, as you know I have a Novakool in the bus, and for that application we absolutely loved it. The boat also had a Novakool when we bought it, an RF8000 (now discontinued).
We had two problems with the Novakool on the boat. First and foremost, it was simply too small. The 7.5 cubic foot model in the bus was great -- it had the right mix of fridge/freezer, and it could hold about two weeks worth of provisions, which was really the limit of our remote boondocking capability anyway based on water and waste tank sizes. So we could always count on being someplace where we could get some fresh groceries every two weeks.
The RF8000 on the boat, however, was only a 6.5 cubic foot model, and, worse, that one foot difference all came out of the fridge (the freezer portion was almost big enough). On the boat, we are often unable to reprovision fresh food for a month or longer, and we expect that problem to just get worse when we start going further offshore. With less than five cubic feet of refrigerator capacity, we were having trouble fitting all our food in the fridge.
The previous owner had worked around this problem by putting a marine-rated chest refrigerator on the aft deck (and if you thought Novakools are pricey, you'll plotz if you price Frigibar marine chest units -- this one retailed for over $4,000). We wanted that space back for a table and chairs so we could eat and socialize on deck, and we ripped out the chest unit and sold it (for a paltry couple hundred on eBay). Besides that, it was 120-volt, too, and had a heated lip seal that ran 24/7, so not exactly efficient.
The second issue with the Novakool was the frosting problem. Again, on the bus, this was not much of a problem. We avoided hot, humid locations for the most part (except when we were chasing tropical storms with the Red Cross), and when we had to put up with them, we were generally able to run air conditioning -- finding power outlets was simpler on the bus, and we also had the ability to run some A/C off the batteries. Here on the boat, however, we are almost always in more humid conditions, and we can seldom run air conditioning. The Novakool needed to be defrosted at least monthly and sometimes more often (on the bus we did it maybe every half year), or its efficiency plummeted and it could not keep the food cold.
The largest Novakool that would fit in the space where the RF8000 lived is the newer RF8500 (IIRC, the 9000 like you have, Tom, was a hair too big in at least one dimension), and that would only have given us another one or two cubic feet of fridge. Plus, we'd still have the frosting problem, After fighting with too little space and losing too much food to spoilage from the frost problem, I finally decided I'd pay the energy penalty of a frost-free household model to solve both problems at once.
Honestly, I did not expect the MS4024 to have any trouble running a tiny 10cf household fridge. I think Haier took a design shortcut here by omitting a start cap. But it was pretty much the only model I found on the market that I could squeeze into the space I had available (barely -- I posted the installation on the blog http://ourodyssey.blogspot.com/2014/05/fridgeapalooza.html (http://ourodyssey.blogspot.com/2014/05/fridgeapalooza.html)). I'm sure something a bit higher end, even if it was a giant side-by-side, would work fine on the MS4024 with no issues. As you know, I've run full-bore air conditioners from SW inverters before, and lots of expensive boats have big household refrigerators and Magnum inverters.
I'm very happy otherwise with my choice. Having 10cf (vs only 8cf in the larger Novakool) is really helpful, and I am enjoying not having to empty and defrost the fridge on a regular basis. So far, energy usage seems to be better than expected, with only perhaps a 5% premium over the much smaller Novakool we removed. If I can just fix this one issue, it will be bliss.
-Sean
Hello, Sean. Glad to see you back on the forums.
I do not have an answer for you. On your 300 watt compressor: 737 watts is one horsepower. Also Ohm´s law: volts times amps equals watts.
Perhaps you might do well to get a separate inverter just for the fridge.
Quote from: Mex-Busnut on July 30, 2014, 12:24:18 PM
Hello, Sean. Glad to see you back on the forums...
Thanks.
Quote
.. On your 300 watt compressor: 737 watts is one horsepower. Also Ohm´s law: volts times amps equals watts.
...
It doesn't really work that way... yes, if you are talking about either input, or output. But an electric motor that consumes 737 watts does not generate one horsepower of mechanical output. 300 watts is the electrical input, and I need to know how big that motor is in mechanical HP, not how many "electrical HP" it consumes (yes, you can measure electrical power in HP, but by convention, we don't).
-Sean
Thanks for the discussion, Sean. Yeah the defrost thing is a pain at times. But you're right, that's much easier taken care of in a bus. I just wish the people at Haier were better informed. I appreciate the info.
I used to laugh at the "boat is a hole in the water that you throw money into ..." jokes -- then I bought a bus. :o
check the Hertz?....wire size too small?
If you measured its Power Factor with a Kill A Watt meter, would that help you choose different start or run capacitors? It seems to me that a lot of Chinese-made electrical items (such as Iota chargers) have lousy PFs on start-up, no big deal if on-grid but a major problem if drawing from a limited power source such as in boats and buses.
John
Quote from: Iceni John on July 30, 2014, 04:27:01 PM
If you measured its Power Factor with a Kill A Watt meter, would that help you choose different start or run capacitors? ...
I don't think the Kill-a-Watt can give me the starting PF, John -- I'd need a scope (which I don't have). It could capture the running PF, but the run cap adds a different lag than what's seen at start.
-Sean
[deleted]
We had a couple of those in the restaurant for short time ours had Bristol Compressor maybe they could help,I use one in the shop from the restaurant and it seems to struggle on start up on a 110 degree day
Quote from: luvrbus on July 30, 2014, 05:56:17 PM
We had a couple of those in the restaurant for short time ours had Bristol Compressor maybe they could help,I use one in the shop from the restaurant and it seems to struggle on start up on a 110 degree day
Thanks, Clifford, that's great information.
-Sean
I do not think I would put a start cap in series with the ptc. You are looking to reduce the starting current and the cap will do that but it will also reduce the current thru the ptc and that will cause it to keep the start winding energized longer while it heats up.
Go with a Potential relay and a cap around 110 MFD. Even the 3 wire all in one Hard Starts are sometimes flakey. As far as picking a potental relay, thats a tough one as the compressor was never speced to use one. Mars (and others) do offer an adjustable relay so you can tweek your pick up and drop out voltages.
Quote from: kevink1955 on July 30, 2014, 07:56:10 PM
I do not think I would put a start cap in series with the ptc. You are looking to reduce the starting current and the cap will do that but it will also reduce the current thru the ptc and that will cause it to keep the start winding energized longer while it heats up.
Thanks for the advice. Just to be clear, though, the "start" winding is always energized -- its a PSC model, with one coil energized full-time direct from line voltage, and the other energized full-time but with a run cap in series. The PTC only shorts the run cap; once the PTC stops conducting, that coil remains energized but with the run cap in series. (I will try to attach a photo of the circuit diagram.) Does that change your recommendation?
Quote
Go with a Potential relay and a cap around 110 MFD. Even the 3 wire all in one Hard Starts are sometimes flakey. As far as picking a potental relay, thats a tough one as the compressor was never speced to use one. Mars (and others) do offer an adjustable relay so you can tweek your pick up and drop out voltages.
So, again to clarify -- you are suggesting replacing the PTC with a two-wire Hard Start based on a potential relay. So rather than the PTC shorting the run cap, the run cap and the start cap will essentially be in parallel until the potential relay cuts out. Is that correct?
-Sean
Sean, it's nice to see your new thread.. Like many I frequent your blog. I do have a question.
Awhile back you mentioned that you were going post your new boat rewire.. The Magnum and dual alternator 24 volt upgrade? I missed the link.. Can you post some details on your rewire/upgrades..
***** simply add a start cap in series with the PTCR, but I don't know how to figure the proper size and rating of the cap *****
Personally I've never had a problem with Hard start run parallel UNLESS it was underrated, never thought about one being overrated - FWIW
Quote from: Zeroclearance on July 30, 2014, 10:49:47 PM
Awhile back you mentioned that you were going post your new boat rewire.. The Magnum and dual alternator 24 volt upgrade? I missed the link.. Can you post some details on your rewire/upgrades..
.
You didn't miss anything -- I haven't gotten it done yet. It's on my (long) list of things to do. The issue here is the diagrams; a text write-up won't make a lot of sense without wiring diagrams, and I have to start from scratch now and climb the learning curve on a new drawing program. A year or so ago I moved off Windows entirely, and, honestly, even when I got a new Windows machine a few years back, I did not bother installing the ancient drawing software I used to do the bus.
I've dabbled with a few of the programs available for Linux, but so far none has proven easy to use for circuit diagrams. I hope to have something in the next couple of months and then I can make the drawings and write the article. I think it will be useful for bus nuts, too, so I might even send it to the magazine.
-Sean
Yes, the start winding on a PSC motor is always in the circuit but puting a start cap in parelel with the run cap and having only the PTC to get it out of the circuit after the motor comes up to speed could be risky. Originaly with only the PTC the start winding current draw would be high and heat up the PTC, with a start cap in the circuit the current will be lower due to the phase shift provided by the start cap so it may not heat the PTC and the cap may stay in the circuit.
I am not recomending a 2 wire hard start. I would go with a potental relay, that would require 3 wires, 2 are avaiable at the run cap Start and Run, the common will neet to be picked up at the compressor.
It's more old school but the potental relay has been used for years,I am kind of suprised that a refrigerator would have a PSC motor. No chance of it starting till the pressures equalise.
Quote from: Sean on July 30, 2014, 09:09:33 PM
Thanks for the advice. Just to be clear, though, the "start" winding is always energized -- its a PSC model, with one coil energized full-time direct from line voltage, and the other energized full-time but with a run cap in series. The PTC only shorts the run cap; once the PTC stops conducting, that coil remains energized but with the run cap in series. (I will try to attach a photo of the circuit diagram.) Does that change your recommendation?
So, again to clarify -- you are suggesting replacing the PTC with a two-wire Hard Start based on a potential relay. So rather than the PTC shorting the run cap, the run cap and the start cap will essentially be in parallel until the potential relay cuts out. Is that correct?
-Sean
Quote from: kevink1955 on July 31, 2014, 09:42:15 AM
.... Originaly with only the PTC the start winding current draw would be high and heat up the PTC, with a start cap in the circuit the current will be lower due to the phase shift provided by the start cap so it may not heat the PTC and the cap may stay in the circuit.
OK, that makes sense.
Quote
I would go with a potental relay, that would require 3 wires, 2 are avaiable at the run cap Start and Run, the common will neet to be picked up at the compressor.
Great, that's what I will do. Just to confirm, the PTC would then have to be removed from the circuit (because otherwise it will just short not only the run cap, but also the start kit), correct? Also, the big question: These kits seem to be commonly sized at either 1/12-1/5 HP, or the next size up at 1/4-1/3 HP. Want to take a guess at which one I need?
Quote
... I am kind of suprised that a refrigerator would have a PSC motor. No chance of it starting till the pressures equalise.
Yes, me too. As I wrote, I think I would not have this issue with a slightly higher-end fridge, because they'd have used the correct setup to begin with. But this model is clearly aimed at a lower price-point at the expense of, for example, Energy Star certification, so I suppose it makes sense that they cut some corners here. I'm happy to add the start cap to the setup, I'm just trying to avoid long-term motor damage from either too much or too little starting current.
Thanks so much for your help.
-Sean
Yes, the PTC would be removed as it would defeat the start kit. If I had to guess the smaller hard start would work, I could not imagine that a box that size would be 1/4 or larger.
I have never used an all in one start kit, I always built them with a potential relay and cap but as long as it has some sort of relay built in it should work.
Do you have a Link to the one you are looking at?
Quote from: kevink1955 on August 01, 2014, 09:18:24 AM
...
I have never used an all in one start kit, I always built them with a potential relay and cap but as long as it has some sort of relay built in it should work.
I would prefer to do that, and I know how to source the cap, but I've never selected a potential relay for an application like this before, and I'm not sure where to start.
Quote
Do you have a Link to the one you are looking at?
I was thinking of maybe the Quality Engineering QSR-15, which seems to be widely available:
http://www.qequality.com/categories/85/HARD_START_KITS/products/179/HARD_START_KITS_FOR_REFRIGERATION.aspx (http://www.qequality.com/categories/85/HARD_START_KITS/products/179/HARD_START_KITS_FOR_REFRIGERATION.aspx)
-Sean
I have used the supco adjustable in applications that I was unsure of the voltage requirements
http://www.supco.com/images/pdfs/Manuals-Instructions/APR5%20man.pdf (http://www.supco.com/images/pdfs/Manuals-Instructions/APR5%20man.pdf)
The link you posted for the all in one also looks good as it contains a relay, cap and overload in 1 neat package.It looks to have 5 wires, I am assuming 2 are line 120v + and neutral and the other 3 are common, run and start.
You would need to keep your existing run cap in the circuit as the compressor was designed for it and it helps reduce current draw (that phase shift thing again). It would be wired to the run terminal and the 120v +
I am so happy I followed this thread all the way through!
Sean, I was looking to purchase a Hailer fridge a few years back. I could not get a clear answer on any of my rather simple questions! I wound up with a 3.8 CF model from Magic Chef. I was running a 1,500 watt inverter in the truck. I noted that on startup it would take about 800 watts for a fraction of a second, then run at 30 to 40 watts.
Hope y'all are well!
Jack
Hello Sean,
Glad to see you posting again!
Hope boating is as fun as bussing!
Here is the Supco 3 in 1 hard start diagrams and sizing if you didn't have it.
http://www.supco.com/images/pdfs/AC%20Hardstarts%20Booklet.pdf (http://www.supco.com/images/pdfs/AC%20Hardstarts%20Booklet.pdf)
Sean! So so great to see a thread started by you! I clicked on it the moment I saw it even though I no ZERO about refrigeration :) Your blog is so interesting. Really enjoying seeing the contrasts and commonalities of boat v.s. bus living. Cool stuff. Ok...back to your fridge issues. 8)
Sorry for the delay here... thanks, everyone, for the help. I had to set this aside for a while as our schedule got a bit tight.
Sounds like I will be ordering a Supco kit and see if that takes care of the issue. At the moment it is more of an annoyance than a major problem. We are otherwise very happy with both the fridge and the inverter, so I'd rather not change either of those out.
Nick, we will be stopping in Cape May on our way south, maybe two weeks from now. If you carry these I'd be happy to give you the business.
-Sean
When you say it isn't an issue except for the devices that don't like the brown out, what devices are we talking about? If they are computers or costly electronics and you are running them off of a generator or inverter, you might want to think about putting a UPS on them. That would solve the brown out issue and add protection to those devices.
Sean-How're Doin? If you were to do it again, would you buy the same refrigerator knowing what you know now? I'm second thinking using the NovaKool 9000. Why-I have it in my bus. And while it worked well, in the two weeks we were out, had to defrost it twice (which isn't such a big deal with the Norcold chest freezer) and let it defrost again when we got back (maybe a deflector in the front to keep the warm air off the coils everytime you open the door?). Being in the mountains, we weren't running the A/C much, hence it was a bit humid inside. I'm thinking maybe a frost free refer. I have nearly 7ft tall X 24 wide X 23 deep to play with. But-since I'm 12vdc, will be running the Magnum load sharing 3000 watt inverter. What do you think? Good Luck, TomC
Quote from: Sean on August 21, 2014, 08:28:24 AM
Sorry for the delay here... thanks, everyone, for the help. I had to set this aside for a while as our schedule got a bit tight.
Sounds like I will be ordering a Supco kit and see if that takes care of the issue. At the moment it is more of an annoyance than a major problem. We are otherwise very happy with both the fridge and the inverter, so I'd rather not change either of those out.
Nick, we will be stopping in Cape May on our way south, maybe two weeks from now. If you carry these I'd be happy to give you the business.
-Sean
Sure Sean,
Would be glad to help you out and sell you the 3 in 1.
Give me a call when you are near and I will deliver it to you
or if you like to stop at our shop your more then welcome!
609-263-2296 office
Quote from: TomC on August 21, 2014, 09:28:08 PM
... If you were to do it again, would you buy the same refrigerator knowing what you know now? ...
I'd have to say "no." It meets our needs, and was the right size for the space we had, but I did not anticipate this hard start issue on such a small fridge. I think the small compressor is what let the designers get away with the PSC design -- the average household 15-amp circuit, even an overloaded one in a small apartment, will have no trouble starting this motor because the surge, as large as it is, is well below the threshold of most HVACR breakers, and the power grid behind it is, well, nearly infinite.
All that said, I don't know how to tell what other apartment-sized units suffer from the same issue. Really all you can do is look inside the back of every one for the circuit diagram. Wish I had done that in this case. Now that I have it fully installed, I'm not going to change it, which is why I am looking for the hard start solution.
-Sean
Quote from: Nick Badame Refrig/ACC on August 27, 2014, 07:15:49 AM
... Would be glad to help you out and sell you the 3 in 1.
Give me a call when you are near and I will deliver it to you
or if you like to stop at our shop your more then welcome!
...
Thanks, Nick. I'll give you a shout when we get close. Not sure if we will dock in Cape May or anchor, but if we anchor, I will try to find a spot to land the dinghy and meet you. No way to get by the shop, unfortunately :-(
-Sean
I was heading towards a Summit FFBF240W which is 73"h x 23.75" wide x 23.5" deep and weighs 150lbs. If on a boat that has nice motion (like a trawler) you can easily control the food inside. But with the truck conversion I'm doing, even though the refrigerator is going to be right over the rear tandem axles with the Kenworth 8 air bag suspension, the ride still won't be the same as a bus. And hearing some that have freon line cracking and breaking on split A/C's made me to this-I just order the NovaKool 9000RFU with 120vac and 12vdc. Delivered to my warehouse-$1,883.00. Not cheap, but it is built in, front discharge of hot air from the under compressor, door locks, and raised ends on the shelves to hold the food in-in other words, it's made for RV. Good Luck, TomC
Quote from: TomC on August 28, 2014, 10:45:30 PM
I was heading towards a Summit FFBF240W which is 73"h x 23.75" wide x 23.5" deep and weighs 150lbs. If on a boat that has nice motion (like a trawler) you can easily control the food inside. But with the truck conversion I'm doing, even though the refrigerator is going to be right over the rear tandem axles with the Kenworth 8 air bag suspension, the ride still won't be the same as a bus. And hearing some that have freon line cracking and breaking on split A/C's made me to this-I just order the NovaKool 9000RFU with 120vac and 12vdc. Delivered to my warehouse-$1,883.00. Not cheap, but it is built in, front discharge of hot air from the under compressor, door locks, and raised ends on the shelves to hold the food in-in other words, it's made for RV. Good Luck, TomC
Tom - Same fridge we have. Ordered it new for about 1300.00. Its a great fridge but overpriced. We have been full timing with it for a year and its held up well. Only thing I don't care for is that it doesn't auto defrost and we have to manually defrost about once a month. Been thinking if I put a fan and a cup of damp rid in the fridge we could go longer without having to defrost. I think that is also the same fridge Sean is replacing....mostly because of the size. He is looking for a 2-4week food supply so he can have steaks when they cross the Atlantic :)
http://baymarinesupply.com/store/refrigeration/marine-rv-refrigerators-icemakers/nova-kool-rfu9000-marine-rv-refrigerator.html (http://baymarinesupply.com/store/refrigeration/marine-rv-refrigerators-icemakers/nova-kool-rfu9000-marine-rv-refrigerator.html)
Its now a little more then what we paid last year from the same place.
-Sean
Bay Marine is where I ordered it from. I had to pay sales tax since it is in California. As to the defrost thing-I have the NovaKool 9000 in my bus and it does seem to ice up sooner then I'd like. On the top evaporator, I was thinking about putting a deflector of some sorts to keep the warm, humid air off the coils a little better. I like the refer, except for the defrosting part. When I do defrost, I put the critical food in my chest freezer, then turn off the refer with a towel inside. About 6-8 hours, it's done. Just wipe down the wet coils and restart it up. Good Luck, TomC
Just wanted to update everyone on the outcome.
Nick very generously came down to the boat in Cape May with a SUPCO 3-in-1 hard start unit, and after helping me on the phone to understand how the old start unit was snapped onto the compressor, I finally got it installed. It's a tight fit in the tiny fridge, and getting to the compressor terminals was a chore. Also, while there is a wiring diagram on the back of the fridge, no colors are listed, so I had a bit of a puzzle figuring out which wires went where -- they used the terminals on the start relay/overload unit as a sort of junction block.
Now that it's been in place for a couple of weeks I can report that we are no longer seeing the dropouts on the inverter output, and the refrigerator itself is working normally and appears none the worse for it. Only time will tell, of course -- an improperly sized start cap can cause premature failure of the motor.
A big thanks to Kevin for helping with the diagnosis and to Nick for running the part down to me and consulting on the installation. This forum will always be #1 in my book.
-Sean
lying Baltimore, MD
Cool stuff. Love to see members helping each other. Time to rename the forum: "busboatconversions.com"
Sent from my iPhone using Tapatalk. Clumsy fingers may contribute to mistakes.