It's block heater day - Tstat question

[MikeP]

After a season of putting it off, I decided to replace my defective block heater today. It's under the mounting bracket for the alternator so that makes it a bit of a chore to get to but I figured I'd do it while my old NECO autopilot waits for it's new transistor!

I don't know what brand the block heater is but I assume it's one of the Kim hotstarts but I'll determine that after I pull it. When I bought the boat it had house-type thermostats connected to the block heaters which looked rather "un-marine-like" so I removed them very quickly. But I'm thinking of installing Tstats for them when I install the new ones. But I got to wondering what real purpose they would serve for me.

I never left the heaters on for extended periods so I don't really see what good a Tstat would do. The longest I recall leaving them on was maybe a couple of hours and the water temp in the block never got above 140. I can understand having Tstats if the block heaters are left on for many hours or days but since I never do that, I can't really see any reason to have them.

Am I missing something? Do some folks leave them on for extended periods where the Tstats would actually be needed to limit the temp? I don't think the heaters in my engines could ever get the temps up past around 140 though I don't know that for sure.

So do Tstats serve a useful purpose for block heaters?

 

[TopHattandTails]

X2 Mike. I'm in the "turn 'em on when you need 'em camp". I usually turn them on a few hours prior to launch and they work great. If I leave them on overnight things get good and toasty- enough to heat oil in 5 gal buckets to flow nicely with the 32vDC pump back into the engines after a 12 hour break from pulling oil in late October in Ohio (the block heaters are a dual source on my boat- for heating the blocks and heating oil at oil change time). But I'm also not sure if I have t-stats or not...

 

[MikeP]

Thanks! I'll just keep the method I've been using - turn 'em on when I need them.

I just finished pulling the heater. It's not a Kim, it's a J Jeb 1500W.

Wasn't really much of a chore. My biggest issue was not remembering how much coolant was in the engine - I only had two buckets and it wasn't enough. I had to go search the dumpsters for something to hold a couple more gallons!

I'm going to run up to the local Diesel shop when they open later to see if they have any of these J Jebs or a suitable substitute. Here are two pics:

First is the side of the block with the alternator bracket in place which covers the block heater. The red and yellow wires go to the heater. Second is the heater itself. (I see I need to do some clean-up painting on the alternator/surrounding area... )

 

[Boatsb]

Dc heaters? 32 volt? Red and yellow would be dc.



By the way a thermostat would allow it to be left on to keep moisture out of the engines if the boat sits for long periods.

 

[jim rosenthal]

I leave mine on once the weather gets cold, but mine are pan heaters, not block heaters.

Someone who originally installed them used the wrong wire- should be black and white, right? I've never heard of 32vdc block heaters, they are always 120vac or 240.

 

[MikeP]

120VAC. You are right, of course, re the wire color. I didn't know about the wire color until it quit - the wires at the heater were covered with electrical duct sealant so the colors weren't visible. I should replace them. Then again, I could just cover the visible ends again with duct sealant.


I just got back from the Diesel shop. I must be getting to old/crochety...

I walked up to the counter with the block heater in my hand; conversation went like this:

Me: I need one of these for an 8V71TI
Tech: What is it?
Me: it's a block heater.
Tech: What do you mean?
Me: What do you mean, 'what do I mean?' It's an engine block heater.
Tech: What's it for?
Me: It's for an 8V71TI
Tech: I mean what does it do?
Me: It preheats the engine block.
Tech: I don't think we have anything like that.
Me: Could you check?
Tech: do you have the serial number?
Me: No, there's no number on this thing.
Tech: I mean the engine serial number
Me: Well, not with me but I could go back and call you with it
Tech: Chris should be here sometime later today. Call back and give him the serial number.
Me: I'll be back at the boat in 10 minutes, I'll just call you with the number soon as I get back.
Tech: Chris won't be here yet.
Me: Can't I give YOU the number?
Tech: Chris does that stuff, call him.
Me: OK, thanks

This guy wasn't some young kid who was just answering phones - he was at least in his 50's or 60s so I would have thought that he could write down a serial number as well as Chris. Apparently not.

Oh well, guess I'll call Chris later...

 

[rsmith]

If I remember right I've seen hot water tank wiring red and yellow down stream of the thermostats

 

[GJH]

1500w is kind of overkill, IMO. I have 1000w (immersion type) on my 8v92's and they keep everything nice and toasty, and dry during the winter. I have T-stats and love them as we like to keep the heaters on almost all the time during the winter here in NC. We open the engine room doors and they will keep the lower level of the boat above 50 degrees even when the outside is in the 20's or below consistently. The big metal stays an even temperature. We close up the ER vents with some plastic foam wind flashing and beach towels, easy to take out before departure (we boat year around).

Now in my case I have the heaters with an immersion thermostat that is a pig tail to the heater, so it adjusts to the engine coolant temp, not the atmospheric temp. Much more ship shape.

Mike, if you still are dealing with morons on this issue, try calling Phillips Temro, maker of mine, they are very helpful and could point you to a dealer in the area. Integrated T_stat is an option on theirs. Here is their fitment guide. Looks like yours is on page 41:

http://www.phillipsandtemro.com/userfiles/file/2013_ZEROSTART_CATALOG_HS.pdf


Or call the Kim Hot start people, I think a lot of DD dealers carry them.

 

[JLR]

Mike - on my 56, I had Kim Hotstart immersion type heaters. They came with button type thermostats that would cut off the block heater when the coolant reached 140 or so. In addition to that, I added separate wall mounted thermostats in the engine room that would turn on and off the block heaters depending upon the ambient air temps in the ER. To that, I added two, three position toggles in the pilothouse with a light. Those toggles would place the block heaters in the thermostat mode, off mode or manual override mode. In the winter up here in New York, I simply set them in the thermostat mode to turn on when the ambient temps dropped below 40 degrees in the ER. I am not yet sure what I will do on the new boat since there is an on/off switch in the ER for each block heater with an idiot light. I might just buy a plug in outlet that has a thermostat built in and use a space heater for ER heat this winter. Still thinking about that one.

 

[MikeP]

Thanks George,

I don't think those on page 41 will fit. The alternator bracket has a narrow oblong slot that just allows space for the external part of the element (where the wires attach) - see pic in my earlier post. The ones in the catalog appear to be round and larger in diameter than the width of the slot in the bracket. I could modify the bracket - that's what drill presses/hole saws are for but I'd rather get the same heater so I don't have to modify the bracket. But I'll look elsewhere in that catalog as well as wait on "Chris" to return my call.

 

[jim rosenthal]

Yeah, I'm sure you'll have a high-quality conversation with Chris. It sounds like the place is run by idiots. If it's run at all. Good luck on that one.

You can try T&S in Crisfield. They aren't a DD dealer, but at least you will get someone on the phone who knows what they are doing, and if they don't, they'll find someone who does.

 

[MikeP]

Two block heaters should be here NLT Fri. $65 each. It required two additional phone conversations that went remarkably like the conversation in the store although they did take the serial number I gave them as per their earlier request. But FINALLY I got patched through to Chris. I told him what I needed and asked him if the previous guy had given him the serial number. He said he didn't need that for a block heater, asked a couple of questions about the configuration and that was that. When I commented that the two other guys I talked to didn't seem to know much about this subject, his answer was, "tell me about it!" So I can say that Chris seems to know what he's doing. The others? Not so much.

 

[MikeP]

Block heaters are here but this didn't go quite as smoothly as the autopilot repair!

Turns out the original type heaters are no longer available and the only types that are have a round, 1 5/8" boss that has to go through the alternator bracket and it's a square peg/roundhole thing. The bracket has a 3/4" wide oblong slot in the 3/8" cast iron bracket. The parts place referred me to a local guy with a plasma cutter and said he'd probably charge me 50 bucks to cut the bracket to accept the boss.

I was on my way over there when I thought about...hmmm....a hole saw. Went back to the boat, broke out my cheapo harbor freight drill press, chucked a 1 5/8" hole saw in it and, taking care to go slowly with plenty of lubricant (the drill press stalls pretty easily with such a load) I was able to cut the hole to accept the heater with no real issues.

So at the moment I'm waiting for the paint to dry on the bracket and alternator and then I'll close it back up. Then I get to do the same thing on the other engine (even though the heater on that one is working fine).

FWIW I have to say that this crummy little drill press has more than paid for itself this year alone! http://www.harborfreight.com/5-speed-bench-drill-press-60238-9067.html I'm not exactly recommending such a junk tool but it has been extremely useful on board. It takes nearly no space and is easy to carry wherever you need it. I did this operation on the aft deck table.

 

[Boatsb]

I have a little delta bench top that I used to use all the time. Now I just run down to my buddies shop and have him use the bridgeport.



Only kidding mike. Im moving the bridgeport to my cockpit next week.

 

[rsmith]

Wait till all the little metal shavings start rusting!!!

 

[Boatsb]

wait till all the little metal shavings start rusting!!!

I only work on brass and stainless

 

[MikeP]

I'm not totally pleased with these block heaters...

The brand is Zerostart, they are 120VAC 1500W heaters, #8601704

They are supplied with a 6 ft (approx) cable, which has a standard 3-wire, grounded 120V electrical plug on one end and an appropriate connector with a two round-prong + ground fastener on the other. See Pic. For this use, the standard plug is cut off and the cable hard wired to the switch.

The cable gets quite warm and, where it attaches to the heater, it gets downright hot. I would estimate the wire gauge of the suppled cable to be 18 at the largest. It actually looks thinner than that to me. The cable on the previous 1500W heater, which attached to the heater with ring connectors, was 12. 18 ga seems much too small for a 1500W load which, though I'm pretty bad at math, seems to come out to 12.5Amps. In my experience, 14Ga cable should be the minimum size for that load.

So I'm not comfortable with the heater as delivered and am thinking about making up a 14Ga cable with some crimped push connectors that will fit on the heater prongs.

I'd like some opinions about this issue. The part of me that has done a good bit of electrical work is saying the supplied cable is wrong for the application; the other part of me is saying that they sell plenty of these things, apparently with no problem so maybe I'm worrying about nothing...

???

 

[GJH]

You might want to call or e-mail them, you may have the wrong cord set for some reason if it is 18ga. They are very helpful. The cord set for my 1000w Zerostarts is 16ga, and that is what they show in their catalog too for all 120 volt heaters . They will be warm right at the heater end, as a result of the heated element right there, but make sure you have it completely connected.

 

[MikeP]

George,

Thanks - I got out my magnifying glass so I could read the writing on the power cord and it is, indeed, 16Ga. Obviously my internal visual estimation algorithm for wire gauge is sadly mis-calibrated!

Tables show that 16 ga is suitable for up to 13A so it's within appropriate ratings. But I would prefer there was no noticeable heating of the wire itself along its length. OTOH, since there is no safety issue, why bother.

 

[MikeP]

How's this for timing?

Yesterday I changed the wire in the new block heater from the 16 ga that came with it to 14GA. Then I turned on both heaters, monitoring the temps to see if there was any real difference in heating ability between the new heater in the port motor and the old heater in the star motor - there wasn't.

BUT, at the 90 minute mark, the GFI main breaker tripped and a quick check showed that the star's block heater had no gone into the same failure mode that the original heater in the port block had exhibited. So the two original heaters had failed within probably 10 hours of use difference. But, as noted by someone - not bad for 33 year old heaters.