Monitoring a Hydronic Heating System?

We had a very simple system on a Cal 46: 45,000 BTU, A header/expansion tank, and a single continuous loop, with air handlers in each of the 2 staterooms and in the main salon. Used simple thermostats to control the fans on the air handlers. No selenoids.

We did run several loops of copper tubing in the hanging locker where wet foul weather gear was stowed. We also put a couple of loops of copper tubing in each head to place towels over--warm and dry, as well as bare copper tubes around the baseboards of the heads. The rest of the tubing was insulated. This worked well in AK.

What I would want to monitor: temp at return to boiler, fluid level in expansion tank, and amps drawn by the pumps, fans, and boiler (fuel pump, ignitor and air compressor).

thataway said:

We had a very simple system on a Cal 46: 45,000 BTU, A header/expansion tank, and a single continuous loop, with air handlers in each of the 2 staterooms and in the main salon. Used simple thermostats to control the fans on the air handlers. No selenoids.

We did run several loops of copper tubing in the hanging locker where wet foul weather gear was stowed. We also put a couple of loops of copper tubing in each head to place towels over--warm and dry, as well as bare copper tubes around the baseboards of the heads. The rest of the tubing was insulated. This worked well in AK.

What I would want to monitor: temp at return to boiler, fluid level in expansion tank, and amps drawn by the pumps, fans, and boiler (fuel pump, ignitor and air compressor).

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You've pretty well described our system. Trouble shooting is dead simple as is reliability. TT's very big boat benefits from a hydronic system similar to a dirt home. Kevin's boat in AK resides in freezing weather thus his monitoring systems are necessary especially given his interests and capability in electronics.

Seattle, Vancouver and Victoria marina areas are pretty benign during the winters but arriving to a warm boat as the very bright electronics oriented OP desires is a nicety. i have a safety concern though. With so many diesel fired boat boiler systems owner or lesser mechanic ( as compared to dirt setups) installations, fire and CO issues should be uppermost in our thinking.

After market boiler specific electronics could well circumvent boiler manufacturer safety systems. System monitoring is one thing and understandably a real plus. System controls another, so as the OP is doing with a professional installer, I encourage readers of this great thread - be careful.

thataway said:

We also put a couple of loops of copper tubing in each head to place towels over--warm and dry, as well as bare copper tubes around the baseboards of the heads.

Click to expand...

That's a very nice system. Our little cabin on the South Island New Zealand and our condo also, both had the bathrooms heated via just the towel warmer bar, and both worked great in the very cold weather (with un-insulated walls).

Arthurc said:

Agreed, you might be able to get a bit of hot air out of a salon fan unit but certainly not the whole boat... As much as possible we are designing to prevent the system from sucking heat from the water heater.

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Twisted and Arthur,

I think you misunderstood me. I'm thinking for simplicity that we use a large domestic water heater basically as a header tank. Example, a 50 gallon tank, which is typically equipped with dual 4500 watt elements.

So when heating the boat from the diesel furnace, the water is still being circulated through the 50 gallon tank. When run off the main engine, same thing. And if run off a genset, then the 9kW elements can supply a certain amount of heat.

If you don't have this common "header tank" then how do you plumb a hydronic system from both the furnace and the main engine?

I see, so the HW tank would only be used for the heating system and not for domestic HW.

With 9kw of electric heat you could probably heat a smallish boat just fine.

The other way engine heat is transferred to the heating system is via a heat exchanger, either a plate or tube type.

Our boat has Webasto 2010...
PO did good installation with 4 zones. Zone control is by thermostatly controlled fans.
Instalation is in series with hot water heater and starboard engine.
Plan to add heat exchanger between domestic heating circuit and engine. Think that there are lots of potential leaks on extensive domestic heating circuit...
Added benifit keeping starboard engine hot is salon deck amd cabin are warm, keeping carpet dry.
Engine is a big heat sink, allowing generous recovery if doors open gor extended periods. keeping interior warm.
Once boat warmed up Webasto only runs few minutes per hour