Russell Clifton
Guru
Today will be the fourth time in four years I have replaced the compressor in my Hurricane II heater. We live on board so it get's lot's of use. Any other users had this much problem with their heaters?
The high and low temp sensors are always going out to the point we keep several spares onboard.
Yes the sensors are called "aquastats", and they are located on the sides if the boiler tank. There is a LOW, HIGH, and OVER TEMP . If any one of the three malfunctions it will shutdown the system.
People I know with Hurricane heaters have had mixed results. Some work fine as others here have reported. Others are total disasters as has also been reported.
Uniformly excellent reviews come from Olympia (Sure Marine) and Kabola. Both are residential boilers at their core.
Olympia and Kabola are great, but both require 110V power and a lot of it, as well as a lot of space as they are not highly integrated. The ITR heaters do not come in 24V or 110V versions as far as I am aware. I had to install the Hurricane II with a DC-DC converter in my 24V sailboat.
I actually prefer the ITR heat exchangers to the Suremarine. I've not had one leak other than at the hose connection (this bit is better on the Suremarine). Be aware that the Suremarine units will not come even close to their stated heat output, you will get maybe 1/3 of the rating.
I've seen some very dodgy installs of the ITR, and those were "professionally" done.
I didn't say anything about Olympia. What I said was the Suremarine heat exchangers do not produce the rated output. 1st, they rate them at a very high water temp, not the more typical temp that the exchanger will see. Second, the rating is the max rating that raw heat exchanger will do under lab conditions (that info from Suremarine). Mainly the fans are too small to produce anything like the airflow required. In contrast the ITR units are rated at a realistic water temp (130 deg) and have much higher air flow. I have 4 Suremarine heat exchangers and 4 ITR heat exchangers and can tell you that without equivocation. The Suremarine are nicely built but need bigger fans, especially if ducted at all, and if you can't maintain 170 deg water throughout the system, derate them by a proportional amount.
I have an earlier version of the ITR cabin fan catalog, and it specifies the same heat output at 110 deg F. Typo? I don't know. 170 would certainly be more reasonable, as the cycling thermostat in the ITR is set to go on at 160 and off at 180.
What I can tell you for certain is the Suremarine specs are for the component alone, not the assembly. That is, the heat exchanger as a component is rated by the manufacturer under lab conditions to do what the graphs say. This is what Suremarine told me directly. Similarly, the fan is rated by the manufacturer for that CFM standing alone. You can look that up from the part number.
Fans are the particular weak point of the Suremarine: they use small brushless axial fans to keep the noise down. This also keeps the heat output down. Axial fans with short shrouds - 20 or 25mm in this case - are very intolerant of any pressure rise, so anything blocking the output - like a heat exchanger or any ducting - reduces the CFM very substantially. Longer shrouds like 50 mm mitigate that to some degree. You can find this in many manufacturer's specs. Of course a radial fan is much more tolerate of back pressure.
The ITR exchangers have much larger fans, with longer shrouds. The air output is considerably higher as an assembly and the difference is not at all subtle. In fact I have purchased 50mm thick, higher cfm fans to replace the Suremarine ones which I will install this spring. CFM in fans is pretty much related to power. I do not know how ITR specs the cfm (fan alone or assmbly?) but I can tell you without doubt the output is much higher.
Similarly the heat output of the exchanger assembly is much higher. On the sailboat I have 3 Suremarine and 2 ITR heat exchangers on the Hurricane II system, on the same loop. The difference in heat output is dramatic. On the trawler, I have 1 Suremarine and 2 ITR on the Zephyr system, again the heat output difference is dramatic. You are welcome to drop by and experience it for yourself. Nothing against Suremarine, I like the people and the company - but don't believe those specs. The fans need to be much larger to achieve that output. The 5kbtu rated air handlers on the sailboat are each blowing through about 2' of duct with one 90 deg bend. I'd estimate the heat output is less than 2kbtu, based on the fact that a 500W electric heater will heat that cabin quicker (they are in the heads and guest stateroom). The ITR exchangers seem to achieve their rated output, guessing from electric heating equivalent.
On power, the Zephyr is spec'd to run at 6.5A. The March circ pump is about 2.5A, and the fans about 1.5A all running. That'd be 10.5A full on, though in practice I measure it at about 9A. For 20 seconds or so during starup, another 5A or so for the igniter. So I'll say 117W. On the Hurricane II, it seems to be about 10 or 11A running. Those are measurements, not specs.
I’ll look at largest fans if some zones are too cool. I have been expecting to reduce the fan capacity in a few spots like heads which are easily over heated.