Flat Plate Heat Exchanger Questions

zugg · 08-03-2009, 11:43 AM

Greetings,

Some questions for people who hava a flat plate heat exchanger:

1 What is the life span of these units--granted that they are flushed after evry use in cold environments?

2 Is there a temp control-or do you just add more cold water when showering?

3 Does the hot water ever become "scolding hot" the longer your engine is on?

4 Who has a circulation pump added to this system? How long does the hot water last, once the engine is off?

5 How well does this system work?

6 If anyone has a diagram and/or pictures of the flat plate heat exchanger, pleas post them here!

Thank you for any useful replies!

Zugg

EMrider · 08-03-2009, 12:47 PM

I have one, but don't know much about how it works. Others here will have far more facts I'm sure. But FWIW........

Quote:

Originally Posted by zugg

Greetings,

Some questions for people who hava a flat plate heat exchanger:

1 What is the life span of these units--granted that they are flushed after evry use in cold environments? Don't know, but I've had mine for 3+ years. I drain water from system before venturing into cold temps, but have never 'flushed' the heat exchanger.

2 Is there a temp control-or do you just add more cold water when showering? Sort of, there is a mixer at the shower and faucet. The new shower design is supposed to work quite well. The thetford I have does not regulate temps very well. It is a piece of junk.

3 Does the hot water ever become "scolding hot" the longer your engine is on? Sort of. Surging and scalding are a problem, and the water is HOT. Gotta be very careful with kids.

4 Who has a circulation pump added to this system? How long does the hot water last, once the engine is off?

5 How well does this system work? Pretty well for basic hot water, but it is sort of all or nothing. Again, the new shower is supposedly easier to regular. I just fill up a solar shower bag with hot water and that works fine.

6 If anyone has a diagram and/or pictures of the flat plate heat exchanger, pleas post them here!

Thank you for any useful replies!

Zugg

My major concern with this design are the hoses that route the coolant thru the heat exchanger under the van. If either of these hoses failed, cracked or got ripped open from road/trail debris, I think there is a risk of losing all the coolant in a hurry. That would leave me SOL. For me the benefits outweigh the costs and hose failure is a risk in many areas.

Rob

JoeyNick · 08-03-2009, 10:23 PM

Quote:

Originally Posted by zugg

2 Is there a temp control-or do you just add more cold water when showering?

You add more cold but after 4 years of ownership I finally installed an anti scald device. I think it's needed.

Quote:

Originally Posted by zugg

3 Does the hot water ever become "scolding hot" the longer your engine is on?

Sort of. It's gets hotter the longer it sits in the heat exchanger. And since most SMB owners take a "navy shower" (get wet, turn water off, soap up, turn water on...), there's time for the hot water to get really hot.

Quote:

Originally Posted by zugg

5 How well does this system work?

The flat plate makes hot water as fast as you can pump cold water through it, as long as the engine is warm.

Quote:

Originally Posted by zugg

6 If anyone has a diagram and/or pictures of the flat plate heat exchanger, pleas post them here!

There's a picture of the old style and new style falt plate heat exchangers in my gallery:

**daveb** · 08-05-2009, 09:54 PM

I got to agree with Rob and Joey. I seem to waste a lot of water trying to get the "just right temp” with the old shower head. The anti-scalding setup seems to be the way to go, at least with the Espar heater. When I use the flat plate with the engine coolant only (engine hot but not running), the hot water just gets colder over the shower time. I've never used the flat plate only with the engine running so I don't know what happens when the engine thermostat opens or closes (or if it even matters). But the Espar cycles, so if the water is not continuously running the water gets very hot while not flowing. When starting the shower flow you have to be careful or you will scream loudly and scramble to adjust it. After adjusting the wand the water starts to get kind of cool. Back and forth. In summer it’s not too big of a deal, only if you’re burning parts of your body off. Overall I can control it to get the job done. Takes practice.

Skywagon · 08-06-2009, 07:57 AM

For what it's worth, we have the flat plate with no tempering valve. With the engine warmed up and in park ,(E-brake on), high idle deployed, after dialing in the water temp you want, the shower stays the same temperature for the entire length of the shower. With the engine off, it's going to get colder as you use up residual engine heat to heat the shower water.

Bill

BACKRDS · 02-24-2013, 03:59 PM

I'm reviving an old topic with a new question. Can someone describe or provide a line drawing about the hose and pump arrangement of a Espar hydronic system, flat plate heat exchanger and the engine coolant loop. Are there extra pumps or check valves? I've been using the espar and flat plate, and after I added a tempering valve we are now happy with the setup. We also take showers with a warm engine (espar off). However without circulation through the warm engine, the shower water gets cooler and cooler. So I want to add an auxiliary 12 volt pump to circulate coolant through the warm engine and the flat plate heat exchanger. One option is to put the aux pump in series, but it will result in some degree of restriction if it is not "on" when the espar is also on, with the espar pump running. I don't know if the restriction will be enough to be a problem for the espar if the aux pump is not on. Any experience here?

What produces the flow from the engine to the flat plate heat exchanger when just driving down the road? Is there a split somewhere downstream of the engine water pump where part of the flow goes to the radiator and part goes to the loop with the espar and flat plate heat exchanger? If so, does the partial stream of flow to the radiator mean less effective cooling for the engine?

So, how does the SMB supplied Espar and flat plate heat exchanger connect with the engine coolant loop?
Thanks, Steve

**daveb** · 02-24-2013, 10:14 PM

Just like the heater core. I've never had a problem with the Espar running with or without the pump running. I will say SMB has had reports of issues. Not in my experience. Also Greg (from lubrications specialists) claimed there shouldn't be a problem if using the Hydronic with or without the pump. At one time I thought the engine running would cause the espar to throw a code and shut down the Espar. It doesn't. If I drive 30 min and the espar time clock is set to 1 hour, it will start up if the engine cools enough.

Hope this helps

sinbad · 02-28-2013, 09:52 PM

When using the SMB factory installed flat plate heat exchanger, I have found a cold shower after a few minutes when the van was stopped. Can someone suggest a 12 volt powered circulation pump which could be switched on when hot water is desired? In this way much more of the engine heat (diesel) could be used to heat the water.

Sinbad

**daveb** · 03-02-2013, 01:10 PM

The pump SMB installed is an Espar product I believe. You can contact Greg at lubrication specialist or SMB should have a contact as well.

http://www.lubricationspecialist.com/

LanduytG · 04-05-2013, 02:37 PM

Sorry I have not been around for sometime to help with the Espar questions. I tried to get SMB to install an anti scald valve. This is how I would do it if it were mine and it sounds like Joey has done it. Install anti scald valve, install aux pump this way when the engine is ho or warm you can get quite a bit of hot water out it before it goes cold. Big plus is the engine does not need to run and you can utilize heat that is already in the engine. One thing many seem to forget is the you will not get instant hot water unless the engine coolant is already hot. If the engines been running its a non issue. However if the coolant is cold and you turn on the Espar and expect hot water you will not get it until coolant temp gets to at least 120° which depending on the outside temp could take awhile. Now this is where I would add a valve in the system, it can be a manual or electric control. It would be plumed in so the engine could be bypassed. We have and electric valve thats works very well for this. Its a 3 port valve and very easy to install. By using a bypass you will have all the hot water you will ever need in just a few minutes even with a cold system. Link below to the aux pumps we like to use. We are also working a control that will automatically regulate the temperature of the coolant going to the flat plate. One other thing I would like to mention and that is use a high quality silicon heater hose. Its not cheap but will out last anything else. We have it if you can not find it locally. This stuff id very soft and pliable and is blue on the outside and red on the inside.

http://www.lubricationspecialist.com/sprinter/

Greg