In last week’s “Toasty Tootsies” post I went over the way our In Floor Heating system works and concluded my explanation with what I thought was a rhetorical question;
“Brilliantly simple don’t you think??!!
Well, based on the number of comments and Emails I received, while our In Floor Heating system might indeed be “Brilliantly Simple” my explanation was NOT! Therefore, let me try and mend this by revisiting our In Floor Heating and do my best to improve my explanation of how this Open Direct type of system works. If I’m successful I think that most of you will come to agree with my assessment that this Open Direct system is indeed “Brilliantly Simple”!
But you will be the judge of that and so Please do add your comments as to how well this second attempt helps you to understand how our In Floor and Domestic Hot Water systems work and don’t hesitate to add your additional questions and things that still don’t make sense to you.
OK, here is my second attempt to show how this all works;
Deeper Dive into our Open Direct System;
One of the Emails I received, (thanks Benjamin), asked the following set of questions that included many of the points of confusion others sent me so I thought I’d use this to frame this expanded explanation of the Open Direct system I used to design our In Floor Heating or IFH and Domestic Hot Water or DHW System.
Benjamin wrote:
If I understood your installation diagram correctly, you run the drinking water through the same pipes as the water for the underfloor heating. Drinking water and “heating water” are identical, or not installed separately. First of all, this is economical because you one water circuit less. But I have a question about summer operation: drinking water and heating are usually installed separately, because in summer mode
you want to avoid hot water flowing through the heating system, and
the water should not stand still in parts of the circuit for a longer period of time to prevent the formation of legionella.
You can probably avoid point a. with valves that separate the entire heating circuit from the drinking water circuit in summer. But if the heating circuit is not flushed for several months during summer operation, legionella can form and then be flushed into the drinking water circuit when the heating system is put into operation. How do you avoid this? Is the underfloor heating completely drained during summer operation modus?
Thank you very much for further information!
First, let me try to resolve some common sources of misunderstanding that Benjamin and many of you mentioned;
I should have emphasized more how the various parts of our overall water systems are separated from each other. In last week’s post I mostly left out the Cold or “drinking” water system so it needs to be understood that this has its own set of plumbing and ALL the water we drink and cook with comes directly from the water tanks to the cold water taps/showers onboard. All the water in our water tanks comes directly from the onboard watermaker so it is as clean and close to pure H2O as is possible.
One of the things that seems to confuse many people at first is to understand that there are only TWO conditions that causes water to FLOW in a plumbing system:
The regular water pressure in the system causes water to flow IF and ONLY IF water is being REMOVED from the system.
There is a continuous circulation loop with its own PUMP that causes water to flow round and round through the CIRCULATION loop.
When neither 1 or 2 is true, there is NO FLOW of water through the plumbing.
The Hot/Warm systems are the ones based on the Open/Direct system on Möbius and this has TWO different but interconnected systems:
The In Floor Heating Mode which provides WARM water to heat floors when wanted.
The DHW Domestic Hot Water Mode which provides HOT water to all the sinks and showers at all times.
I have modified the following illustrations from last week’s post to show a clearer picture of how these two systems work.
When no Hot water tap is open there is NO Cold water entering the system. However, when one of the In Floor thermostats turns on a Zone Circulation Pump, warm water then flows out of the Calorifier, through the in floor PEX tubing and back into the Calorifier. This is a continuous loop so warm water is flowing through the floor tubing anytime the circulation pump is running.
The DHW system always takes priority so whenever a Hot water tap is opened, the system works like this in DHW Mode. When any HOT water outlet at a sink or shower is opened, the regular pressure in the Cold water system which runs about 60 PSI, causes Cold water to enter and flow through the PEX tubing in the floors to refill the hot water that has been removed from the Calorifier. When the Hot water tap is closed the system automatically reverts back to In Floor Heating Mode and the Circulation Pump causes Warm water to circulate though the floor and keep it toasty warm. To answer another question I received and as should now make sense, we do not actually “drink” water going through the DHW or In Floor Heating, though there would be no problems if we did.
It can initially be a bit confusing because when Hot water is consumed (taken out of the Calorifier by turning on the hot water at a sink or shower) and the system is in DHW mode as per above, it is necessary to replace the water that has been removed from the Calorifier so Cold “drinking water” does enter the DHW system. This is exactly the same as in ANY home or other setup with a Water Heater or Calorifier; when Hot water is taken out, it must be replaced with water from the Cold water supply.
In operation this works extremely well and does so automatically by design. Anytime Hot water is wanted, the Open Direct system ensures that this takes priority and Hot water flows from the Calorifier to the tap or shower as long as it is open. As soon as you close that tap and are no longer needing Hot water, the system reverts to In Floor Heating Mode.
Summer vs Winter:
The difference between Summer and Winter is that in Summer/hot weather when the In Floor Heating is turned off, the IFH Circulation pumps never turn on so no water is flowing through the floor UNTIL a Hot Water tap is opened. Said another way, the ONLY time water is flowing through the floor PEX is when the system is in DHW Mode because a Hot water tap has been turned on. The rest of the time, there is NO water flowing through the floor tubes.
This turns out to be part of the “brilliance” of this type of system in my opinion because the design ensures that the In Floor Heating automatically adapts to whatever the weather is. HOT water ONLY flows through the floors when it is needed and the circulation pumps turn on in colder weather. NO hot water flows through the floors in warmer weather because the circulation pumps never turn on.
This sets up the ideal system as it ensures that the water in the PEX tubing is always being refreshed and is never standing still for any length of time.
Better yet, in hot weather, when you are using DHW and there is water flowing through the floor tubes, it is absorbing some of the heat in the room or from sun shining on the floors and so that by the time the water gets to the Calorifier, it is now a bit warmer so you save energy in the Calorifier because the replacement water has already been warmed up and does not take as much energy to heat up to whatever temperature you have sent the Calorifier to maintain.
Once this all makes sense I think you too will see just how “brilliantly simple” this Open Direct system is. It is completely automatic, no valves or switches to change, no need to drain the system or do anything else other than keep using everything on the boat/house as you always have.
Trust me, it does take a while to figure this type of system out. It is one of those things where it is very simple but ONLY after you understand it! To begin with, it can be VERY confusing! My suggestion, and what I used to do a lot of, is to draw out a schematic for yourself and trace the flow of water in the different scenarios from summer to winter and from In Floor Heat Mode to DHW mode and I think you will quickly see how it works.
Hope this helps and if it still doesn’t make sense just send me additional questions in the “Join the Discussion” box below to let me know what’s confusing or not making sense and I will do my best to answer them all as quickly as possible or in next week’s post.
Thanks for your patience with this not always so clear ex teacher!
Welcome to this first Möbius Update post of 2022! I hope you have 2022 off to a great start already as we work to do the same here aboard the Good Ship Möbius. I am slowly warming up to getting back to weekly blog posts here so thanks very much for your patience in waiting for this first one of the new year. I’ve been warming up particularly well now that I have the in floor heating all working which I think may well be Captain Christine’s favorite feature so far.
And apparently she’s not the only one as Ruby & Barney have discovered how well the in floor heating heats up their little doggie beds.
With the weather getting colder since our return at the beginning of December from our 2 months back in Canada and the USA, I’ve been mostly working on getting all the Domestic Hot Water or DHW systems fully operational and all the various bugs worked out. I’ve received a number of questions about how our DHW system works and what components we have installed and a lot of interest in the in-floor heating system we’ve installed and that’s what Ill do my best to cover here in this week’s update.
Domestic Hot Water System
Our DHW system is pretty straight forward so let me cover that first.
There are just three basic components of the DHW System: Kabola KB45 Ecoline Combi diesel fired water heater/boiler
IsoTemp 75L Calorifier
with 3 internal heat exchangers
Hot Water circulation Loop that runs around the circumference of the boat
The Kabola is the primary heating source for the whole DHW system as it is eXtremely efficient, quiet and very trouble free.
Ours is the “Combi” model which means that it has two separate heating loops inside. The primary loop heats up the water in the IsoTherm Calorifier which holds all the DHW for the boat and the other loop heats up the fluid going to the four air handlers which can heat the air in each cabin if needed. This view of the back of the Kabola shows the primary boiler loop Supply/Return connections at #1 & #2 and then the secondary loop flows in/out of #5 & 6. The Primary loop has a built in circulation pump that constantly circulates the antifreeze/water fluid and a thermostat turns the burner on/off to keep the fluid at whatever temperature you set.
The secondary “Combi” loop has an external circulation pump that is part of the Webasto AirCon/Heating system.
I’ve removed the front of the burner to show you how the internal heat exchangers work. The large black tank you see on the Left contains all the antifreeze/water fluid and the diesel burner is inside the Grey tube on the Right.
The larger diameter tubes/holes on the top are the secondary loop and the larger number on the bottom are the primary heating loop. The Kabola is super simple to operate, just turn it on, set the thermostat to be whatever degrees you want the internal fluid inside the boiler to maintain and then pretty much forget it. When the fluid temp goes down the burner automatically fires up, heats the water a bit past the set temp and then shuts off. Could not be simpler or more efficient. Now let’s follow where the heated fluid as it leaves the Kabola and flows over to the heat exchanger loop inside the Calorifier.
This cutaway view shows how our IsoTherm Calorifier is similarly multi purposed with three different sources of heat to keep our DHW nice and hot. There are two loops of SS pipes on the bottom here, one which has the fluid from the Kabola flowing in/out of it and the other loop a similar antifreeze/water fluid flowing through from the Gardner engine’s “cooling” system. The top most loop is a 240V electric heating element that we can use if needed.
All SS construction and the outside never even gets warm so the heavy insulation has been working very well and the Kabola does not need to fire up very often to keep the water nice and hot all the time.
Turning the Calorifier above around and looking at the outside this sketch shows the three pairs of In/Out connections; one for the hot fluid from the Kabola, one for the hot fluid from the Gardner (when it is running) and then the Cold Fresh Water In and DHW Out. The end of the Calorifier in the illustration above is under my hand and if you look closely (click to enlarge any photo) you can see a Yellow ring labelled “Engine Water” on the far Right and a White ring on the Left labelled “Kabola White” On the top Right the Red Label marks where the Hot Water comes out through the black wrapped insulated pipes which are split into one line going to the DHW loop and the other with the bottom Left Mixing Valve going to the In Floor Heating loops. Closer view of the adjustable Mixing Valve which controls the temperature of the water going out to the In Floor Heating system which wants warm not Hot water, usually about 55C/131F whereas the DHW runs about 65C/150F. To make sure there is always hot water ready to come out of each sink and shower, the DHW flows around the whole boat in a continuous loop of insulated pipe. In this schematic the DHW loop is on the Right hand side and the In/Out to the In Floor Heating is on the Left.
I will get back to the In Floor Heating a bit later below but the key point to keep in mind is that the In Floor Heating is all part of the same DHW system.
To keep the DHW flowing through the hot water loop feeding each tap and shower, this magnetically coupled impeller pump is very small, about the size of your fist and is highly efficiency with very low power consumption and absolutely silent.
We now have very hot water readily available at every tap and shower onboard and we are both eXtremely pleased with how well the whole DHW system has been working.
In-Floor Heating or IFH
Winters here in southern Turkey are rather mild compared to many locations with lows down to 8C/46F a few nights and day time highs as much as 20C/68F but winter is also when we get rainy days and so can get chilly and so the real star of our DHW system the past while has been having nice warm floors throughout the boat to keep us toasty warm.
It has taken me some time to get it all adjusted and working properly but it is now running flawlessly and silently so let me walk you through how this system works.
As with the DHW system above, the In Floor Heating or IFH is a very simple system with the following main components:
An Azel I-Link controller with three thermostats for each IFH zone on the boat, one in each cabin and one in the SuperSalon. A pair of SS manifolds, top Red one where the Warm water (about 50C/122F coming in at the top and then the Returning slightly cooler water exiting out the bottom Blue manifold. Each of the I-Link thermostats controls one of these Taco 3 speed 1/25HP circulation pumps which circulates the fresh DHW water from the Calorifier through the PEX tubing that runs in loops underneath all our floors as needed to keep our tootsies nice and warm. We worked out these serpentine patterns of PEX tubing in each of the three Zones to provide an even distribution of heat wherever there were bare floors and not under the built in furniture. This is in the Master Cabin; Head/shower lower Left, bed center Right. This is how the PEX tubing was laid down before the 10mm marine plywood floors were installed. Serpentine grooves were cut into the foam with a router. Foil tape was set into the groove in the foam and then the 15mm PEX tubing was press fit into the groove. Here is how it looked in the forward end of the SuperSalon.
Let’s take a minute to walk through a brief explanation of how the In Floor Heating system works.
For our IFH system I decided to use what is called the “Open Direct” style as it is incredibly simple and efficient. OPEN in this case refers to the fact that the IFH system is “open” to the same DHW that we use onboard for sinks and showers. A “closed” system would be like the loops of antifreeze/water that the Kabola uses to heat up the water in the Calorifier.
DIRECT refers to the fact that the fresh warm water flowing through the PEX tubing is heating the floors directly, not through a heat exchanger like those in the Calorifier. This simple schematic adds the details of how the IFH portion of our DHW system works. Warm water coming out of the Calorifier via the mixing valve is pumped on demand through the PEX tubing in the floors by the Taco circulation pumps. Part of the simple brilliance of an Open Direct system is that the DHW always takes precedence so anytime you turn on a hot water tap or the shower, hot water is diverted to them until shut of when the warm water returns to circulate through the floors as needed. Huh? How does THAT work you ask? The following two illustrations should help make sense of this very simple but initially a bit confusing system works.
This is In Floor Heating Mode that happens whenever the thermostat for this IFH Zone turns the circulation pump ON and warm DHW is pumped through the under floor PEX tubing in that zone and then returned back to the Calorifier (Water Heater). Keep in mind that even though the whole DHW system is pressurized to about 4 Bar/60 PSI in this mode the ONLY way water flows is IF the circulation pump is running. Even though it is available, Cold water cannot enter the system when the pump comes on unless someone is taking hot water out of the system by taking a shower, doing dishes, etc..
When a Hot water tap is opened then the pressure drops and the system reverts to this DHW Mode and Hot water flows out of the Calorifier (Water Heater) to the HW tap and Cold water flows into the system to replace it.
The cold water goes through heating tubes within the floor on its way to the water heater. This flow pattern provides limited free cooling and other benefits. Stagnation is prevented and priority is given to the domestic hot water use over the space heating use. A small amount of free cooling is realized in the summer.
Note that NO additional equipment, parts or power is needed to make these two modes work automatically.
Brilliantly simple don’t you think??!!
I found these beautiful SS manifolds on Amazon for a great price and they made the whole plumbing of the system very straightforward to install and control. Red handled ball valve top Left is where the warm water from the Calorifier flows INTO the system and is made available to each of the three Red Flow Control Meters/Valves and into the PEX fittings on the bottom.
Cooler water from each continuous PEX loop flows into the bottom three fittings, each with the White capped control valve and then OUT the Blue ball valve and back to the Calorifier. Each continuous loop of PEX in a zone has one of these Red Flow Meters that you adjust to get the correct flow rate, which is about 1-1.5 L/min for our zones. Each ball valve has a temp gauge so you can check the differential of the water temp coming IN and how much it drops going OUT. Ideal is about 50C/122F coming in and 40C/104 going OUT and you adjust this via the Mixing Valve on the Calorifier. Here is what the whole IFH manifold looks like when assembled and installed with the three Taco circulation pumps.
These Taco pumps are pretty much bullet proof and are miserly power consumers as they are very small 1/25HP AC motors. The Taco pumps are absolutely silent and can be run at one of three speed settings to get you the flow you want. They are also dead quiet and you can only tell they are running by watching the flow meters. This Azel I-Link controller is the brains of the IFH system and takes its orders from one of the three thermostats conveniently located in each Zone. Each thermostat is very easy to adjust and provides a full set of information of room temp, floor temp, when the “heating mode” or pumps are on, etc.. Here is what one looks like in operation today. Room temp is 22.3C/72F, Set Point is 24C, floor temp is 49C. Each Zone has one of these little temperature sensors installed which connects to the thermostat of that Zone so it and the controller knows when to turn the circulation pump Off/On. The main control box of the I-Link system is carefully tucked away into a small alcove in the Ship’s Office where it is well protected but easily viewed by opening the cupboard door. Red lights on the far Right indicate when one of the 3 zones is working (pump on).
And that is it! Just like the Kabola boiler, this is a “set it and forget it” system and has been working flawlessly and very easy to adjust as we learned what temps we liked in each zone.
You have to experience it to understand just how fabulous Toasty Tootsies are when the weather turns colder outside!
And that’s a wrap for this week, the first blog and Möbius Update of 2022 is done and dusted!
Hope you enjoyed it and please be sure to tell me if you did or didn’t and add any other questions in the “Join the Discussion” box below.
I’ll do my best to be back again next weekend with another Möbius Update for you and thanks again for your patience in waiting for this one to go live.
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