View Full Version : Adding Second Heater need ideas

03-18-2011, 10:59 AM
So I got in on that HeaterCraft group buy from another forum and not its time for the install. I've searched through a few threads and found some good info on where and how to mount the vents/hot tubes and the core itself. The thing i'm trying to figure out now is how to tap into the hot water for the new core.

I figure there are basically two options, one would be to run the new core in series with the other heater core and the other option is to tee off of both the supply and return lines basically running it in parallel. Does anyone out there have any experience with this or any suggestions? Easiest would be the series option but i'm worried the water won't provide enough heat to the second core in the series. Parallel wouldn't be that hard either but i'm not sure if just T'ing the lines is the right approach.

My boat is a 2005 X-45, the stock core is up under the driver seat and its a dual outlet. My new core is a 4 outlet and i plan on putting it under the back port seat, between the batteries and rear storage locker. The engine is the caddy so the block is fresh water cooled with a heat exchanger. I also bought the y hose fitting for the return line of the heater to help with hotter heat at idle, but i don't think i can use it with my engines heat exchanger setup.

Any ideas would be greatly appreciated, thanks in advance. I will try to post pictures of the progress as i'm sure other people will be doing this in the future.


03-18-2011, 11:20 AM
I would guess you are going to need more than stock flow for either a parallel or series setup to make the best use of two exchangers (at least at idle). If your boat is available right now, you could measure the water temperature on the input and output of the exchange while in oration. That would give you an idea of what the second exchanger would get in a series setup. In parallel I would be afraid the flow would be so low in each exchanger that you may not get a very hot output. Particularly at idle and particularly since you cant use the 'Y'.

Not sure if anybody has tried this, but seams to me if you dump the water to ambient pressure instead of back into the engine, you could get some awesome flow. For example, you could install a second bilge output on the hull that just spills water post heat exchangers. You would want to check to be sure that did not reduce engine cooling capacity, but I would not think so considering the water you extract is has already been heated.

03-18-2011, 11:45 AM
Thanks for the reply, unfortunately i do not have the boat ready for the season yet so i can't measure temperatures. Also, i can not dump to ambient since its antifreeze going through my heater cores on the closed loop side of the cooling system.

Looking though heatercraft's installation manuals it seems they recommend running in series when adding a second heater. I will be giving them a call later today to see what they say.

03-18-2011, 01:45 PM
Engine Flow will not be effected if you have 1 heater core or 2 cores or say 5 cores. The hose running to core or cores in series will return to the engine eventually and start re circulating. The Return will generally be to the water pump and the hose to the core will be from the block. If you didn't have a heater the lines where both hoses go would be capped off. The water pump will still have plenty of cooling capeability to run multiple cores. The hose running water/coolant to the cores will not have a ton of pressure. Pressure is bad for cores.

Personally I would disconnect the return hose and put a small hose running it to the inlet of second core and the long return off of core 1 goes on core 2.

It is a total waste of money and parts to run the system parallel or having y valves etc.

Running in series will NOT damage your boat and still will produce the same heat off of a core. The only difference is you will have twice as much.

03-18-2011, 02:32 PM
Okay thanks, that's what i was leaning towards. Seems way easier to just run the series setup. When you say small hose, you mean short correct? Not smaller diameter?

03-18-2011, 10:39 PM
Rule number one is that the more complicated the plumbing the easier to stop up the pipes. Rule number two is always remember KISS---keep it simple stupid.

03-25-2011, 10:38 AM
Thanks for the input guys, I went with the series installation. As of now i have everything plumbed up and mounted. The only thing left to do is wire up the system which i will hopefully be taking care of this weekend. Here are a few pictures of the holes...65290



I'll get a few more of the final product this weekend.