Espar Hydronic System - Domestic Hot Water

[Hello Below]

I recently took possession of a Hunter e33. I had the dealer install an Espar D5 hydronic system. It has 3 fan heaters. Two of the fan heaters (V berth and aft cabin) are under the control of their own fan speed switch (high/off/low). The third located in the main salon and is controlled by a thermostat. There is no on/off switch for this fan heater.

The domestic hot water system (Kuuma) can be heated by 120v AC when plugged in, engine heater when underway or the Espar hydronic system. My problem is that in order to have domestic hot water when not plugged in and when not underway, I have to turn the thermostat up and thus have the Espar circulate hot water through the Kuuma water heater. This subsequently turns on the fan heater located in the main salon. Good in cold weather. Not so good in the heat of the summer.

Do other Espar owners have this problem or are they plumbed or wired such that they can heat water without heating the main cabin?

 

[Tim R.]

The domestic water should have it's own loop so it does not circulate thru the boat. That is how my a hurricane hydronic heater works. Also, even if it did circulate through the boat, the fan would not come on unless the thermostat called for heat. All of our fans are controlled by a thermostat and variable speed PWM controllers.

You should be able. Add a "summer" loop that will bypass the fan units.

http://itrheat.com/wp-content/uploads/2011/08/HurricaneIImanualRevMar2011_000.pdf


See page 7-6

 

[Hello Below]

Tim, thanks. Very helpful. I definitely have a 3 way valve plumbed in and I also have the two valves to gate the engine heat exchanger in the system, as shown in your link Figure 7-2. I will investigate to see if there is a tee and summer loop also. It may all be coming together. I am not sure if the water heater I have (Kuuma) has an aquastat to call for heat from the furnace. If it does, I am not sure that I want hot water available 24/7 when I am at anchor or rather only on as needed.

 

[Tim R.]

I have not yet installed the domestic HW part on mine. It is an on demand system though. So when we need HW, we will turn on the heater and then shut it off when done.

 

[Stu Jackson]

As you described it, the water HAS to go through the coil with the fan in the saloon. Find a way to put a toggle I/O switch in the fan circuit. The hot water will flow through the coil, but the fan won't blow the hot air. No plumbing changes required, should be easier. KISS

 

[Tim R.]

As you described it, the water HAS to go through the coil with the fan in the saloon. Find a way to put a toggle I/O switch in the fan circuit. The hot water will flow through the coil, but the fan won't blow the hot air. No plumbing changes required, should be easier. KISS

This will work except that the heaters water pump will continue to circulate hot coolant throughout the boat. This alone will raise the temp in the boat. For the best efficiency and to keep the boat as cool as possible, install the summer loop if you do not already have it.

It sounds like you may have it but just have not found the valves yet.

 

[Maine Sail]

I recently took possession of a Hunter e33. I had the dealer install an Espar D5 hydronic system. It has 3 fan heaters. Two of the fan heaters (V berth and aft cabin) are under the control of their own fan speed switch (high/off/low). The third located in the main salon and is controlled by a thermostat. There is no on/off switch for this fan heater.

The domestic hot water system (Kuuma) can be heated by 120v AC when plugged in, engine heater when underway or the Espar hydronic system. My problem is that in order to have domestic hot water when not plugged in and when not underway, I have to turn the thermostat up and thus have the Espar circulate hot water through the Kuuma water heater. This subsequently turns on the fan heater located in the main salon. Good in cold weather. Not so good in the heat of the summer.

Do other Espar owners have this problem or are they plumbed or wired such that they can heat water without heating the main cabin?

You will ideally need to add an aquastat to the water heater and have a secondary circulator if you don't want heat in the cabin loop. You can still use a single loop, but valve off the heaters and just not turn the blower fans on. The problem will be in the in-between seasons when you want both but don't want to get cooked out of the cabin. Basically anaquastat is a thermostat for a hot water heater telling the boiler when to turn on and circulate water to the tank.. It is the ideal situation but is a more tricky install as you need a second "zone". You may need to tee into the supply to get an aquastat into the tank water as your only well is being taken up by the electric probe..

 

[Hello Below]

Next trip to the boat will be an investigative one. I like the simplicity of the on/off switch on the salon fan heater, albeit with all the limitations that comes with it. If there is already a summer loop plumbed in then maybe an additional circulator and aquastat will be in the cards; otherwise, that may be put on my longer term project list.

 

[DeniseO30]

There are number of ways the problem can be solved. "Primary secondary piping" is most often used with "on demand" type heating units. Separate circulators that have check valves should solve the problem.

this is just a "typical" layout, as you can see, each heating loop is able to get it's heat from the heating unit without affecting the other loops. Of course one of those loops would go through the heat exchanger of the WH.(more piping)

I don't see your type of application much different from a typical land based system, other then size. Viewing Tim's diagram It really looks the same as a on demand type system.

I realize smallness and cost are primary reasons for such a poorly designed setup, so you may wind up just using manual valves to do the switch over. If you want it all to work properly you would also need the controls and wiring.
http://www.taco-hvac.com/uploads/FileLibrary/101-052.pdf

All the above is based on 120 & 24 volt AC. so most of it may not even be wanted on a boat. But hopefully, it will give you some insight into hydronics

 

[Hello Below]

Thanks Denise. It looks like you inserted an image just below "(more piping)" that doesn't show up on the post. Maybe you could send it by email to me?

 

[DeniseO30]

http://www.comfort-calc.net/primary-secondary_piping_tutorial.htmlI'm sorry! here's the link
http://www.comfort-calc.net/primary-secondary_piping_tutorial.html

 

[Hello Below]

Next trip to the boat will be an investigative one. I like the simplicity of the on/off switch on the salon fan heater, albeit with all the limitations that comes with it. If there is already a summer loop plumbed in then maybe an additional circulator and aquastat will be in the cards; otherwise, that may be put on my longer term project list.

Well simple is as simple does (or something like that). The dealer did put an on/off switch in such that when in the off position none of the fan heaters will turn on. This only hot water more or less. The coolant still goes through the heaters but little heat is removed with the fans off. I think after warranty I will install a simple summer loop. Because we don't want or need hot water 24/7, at anchor/mooring ball, an aquastat is not in the plans.
Thanks all.

 

[Mark Maulden]

I had an espar hydronic system 15 yrs ago with three heater fans in a Gulfstar 44 cc. I also installed an "Everhot" hot water heater and everything was in one simple series loop. I could switch the heater on/off without requiring heat if hot water was wanted. The reason I put everything in a series loop is that the Espar would not then short cycle as the "Everhot" was a good sink. I could control each fan if necessary. Worked out well. Maybe the later heaters can stand short cycling better........

 

[Hello Below]

I had an espar hydronic system 15 yrs ago with three heater fans in a Gulfstar 44 cc. I also installed an "Everhot" hot water heater and everything was in one simple series loop. I could switch the heater on/off without requiring heat if hot water was wanted. The reason I put everything in a series loop is that the Espar would not then short cycle as the "Everhot" was a good sink. I could control each fan if necessary. Worked out well. Maybe the later heaters can stand short cycling better........

Thanks Mark. Your right about short cycling. Although the national Espar dealer claims the furnace won't be harmed, he did say to wait till it was out of warranty. Go figure. So for now and maybe forever I will sply use the fan heater switch to keep most of the heat out of the boat as required.