Heat Exchange Pump

Submitted: Monday, Apr 25, 2011 at 19:46
ThreadID: 85862 Views:2790 Replies:3 FollowUps:6
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Happy Easter all

We just returned from our Easter camping trip and my Twine under bonnet shower let me down big time and the Mrs was not impressed by having luke warm water for her showers. I have already emailing Twine to find out some stuff but my questions/comments for now until they get back to work is:

1. Do they have any serviceable parts inside the heat exchange unit? Is there a filter or something in there? I always have sand blocking my shower head even though I have a filter at the pump end?

2. I had to reduce the flow to just about nothing to get hot water out the other end, this was after running the engine for at least 30 min and it was sitting at normal operating temp, maybe the coolant is not getting to where it needs to go in the exchange unit.

3. My current pump is pumping at around 17l a min at 35psi but this is a complete overkill, can anyone recommend something else that won't break the bank, I have had this pump for a good 5 years and it's never missed a beat.

Thanks all
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Reply By: Dust-Devil - Tuesday, Apr 26, 2011 at 00:42

Tuesday, Apr 26, 2011 at 00:42
I can't stand it any longer.

(a) Your Heading states 'HEAT EXCHANGE PUMP'

(b) Then you say your Twine under bonnet shower let you down.

(c) Then in the next breath you are on to the internals of the Twine including sand filters.

(d) Bingo! you then latch onto the obvious - coolant circulation problem.

(e) When I think you are on the money you switch to the water pump.

I'll just put your comments down to SWMBO has ear bashed you into 'shock mode'.

You say you have had the 'pump' for five years, so I am guessing that you have also had the Twine for five years and all has been well until this trip. Your water pump sounds just fine seeing as how you have had to reduce the flow to get it 'warm'.

Your brief mention of the coolant being a probable cause of your problem is, I believe, spot on. Not being able to see the vehicle I am in guess mode, however I am willing to place a dollar on the heater coolant control tap/valve.

Hot water heaters of the Twine type are usually heated by the vehicle heater coolant after it has passed through the heater.

So its possibly one of the following: (i) You forgot to turn on the heater inside the vehicle (ii) you turned on the heater, however the aforementioned tap/valve didn't activate either because it is stuffed or the control cable has come off, or (iii) you have a blockage in the heater coolant line.



AnswerID: 452312

Follow Up By: Member - Troll 81 (QLD) - Tuesday, Apr 26, 2011 at 08:41

Tuesday, Apr 26, 2011 at 08:41
Sorry if my post didn't make sense to you

Where I was going with the sand was is that I was wondering if there's a filter of some sort in the heat exchange unit due to always having to clean the shower head sand blockage. I do allot of beach camping and wondering if there's sand in the system somewhere.

The twine was already on the car when I got it so who knows how old it is.

The heater dial is set to the hottest setting and if I turn the fan on hot air is coming out of the vents so I don't believe the problem is with the dial.

I am pulling the heat exchange unit out today to have a bit of a closer look.

Thanks again
FollowupID: 724994

Follow Up By: Dust-Devil - Tuesday, Apr 26, 2011 at 12:33

Tuesday, Apr 26, 2011 at 12:33
Ok! so your Twine is heated via the car heater and the car heater is heating the car in the manner it should. That eliminates one possible cause.

The next thing to try is to get the vehicle engine up to operating temp with the car heater turned off, place your hands around the coolant inlet and outlets on the Twine whilst having a third party turn the heater control switch fully on. You should feel both inlet and outlet heat up almost instantaneously. If it does then, that eliminates the coolant coil in the Twine.

You said, you had to turn down the pump flow to get the water warm. This doesn't indicate a problem with the pump.

FollowupID: 725004

Follow Up By: Member - Vince M (NSW) - Tuesday, Apr 26, 2011 at 16:30

Tuesday, Apr 26, 2011 at 16:30
I agree with the above & have a ten year old twine heat exchanger, & it works great, but a couple of extra things to check
1) my patrol has to be at 1200rpms + to have good hot water
2) once my heat exchanger blocked up with calcium (on the fresh water side) soaked it in CLR & has been fine ever since I've heard this is common in hard water areas & have a look in a kettle in these areas the white beads are amazing & this could be your sandy stuff (as you said you are using a filter)
3) to regulate water better I fitted a mini shower mixer on the bull bar cold & hot so water comes from pump to a T one hose to cold side of mixer the other to heat exchanger than to hot side of mixer so you regulate as you require this has stopped a waste of water when its to hot or cold & is as easy as at home to regulate
good luck Vince
FollowupID: 725035

Reply By: ABR - SIDEWINDER - Tuesday, Apr 26, 2011 at 09:58

Tuesday, Apr 26, 2011 at 09:58
Hi Troll

I use a fine irrigation in-line filter from Bunnings on my intake.

I then circulate the water in the jerry can until it is hot and once happy with the temperature I switch the car off and use the shower.

I have found that running the car while showering produces scalding water if you stop the flow for a few seconds and my not be hot enough at other times.


Derek from ABR
AnswerID: 452328

Follow Up By: ABR - SIDEWINDER - Tuesday, Apr 26, 2011 at 10:23

Tuesday, Apr 26, 2011 at 10:23
FollowupID: 724998

Reply By: Member - Troll 81 (QLD) - Tuesday, Apr 26, 2011 at 12:26

Tuesday, Apr 26, 2011 at 12:26
I fixed the problem today and installed a small ball valve to control the flow. Now I can turn it right down and still have a steady flow of water coming out.

The inline filter is a great idea Derek I will do that as well

AnswerID: 452340

Follow Up By: Dust-Devil - Tuesday, Apr 26, 2011 at 12:42

Tuesday, Apr 26, 2011 at 12:42
Are you saying, that by installing a ball valve, presumably in the pump line, you have fixed a problem that has never existed in the same equipment for the past five years, and then magically manifests itself when you last used the water heater a few days ago.
FollowupID: 725006

Follow Up By: Member - Troll 81 (QLD) - Tuesday, Apr 26, 2011 at 14:36

Tuesday, Apr 26, 2011 at 14:36
I put the ball vale at the outlet side of the exchange unit so it will slow the flow down and build more water up in the heat exchange unit.

The only thing I can put all this down to is that we mainly camp in summer and maybe with the change of temp it's much more noticeable now than ever before.
FollowupID: 725017

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