Another Hydronic Thread?

[Crlefley]

SO… Ive been doing a lot of digging on here. Ive used the search function, And I have a build thread. So I’ll keep this specific.
Looking into Hydronic. My components list is as follows.
China Boiler (or name brand one maybe?)
Flat plate exchanger (for separating the fresh water heat loop from the engine coolant heat loop)
A couple pumps (24v)
Some Pex obviously
An eBay manifold.
Expansion tank.
Here is a rough drawing of what my thoughts are. Am I missing anything?
The in floor heat portion of this is going to be very small. I intend to run a mini split, as well as one, maybe two diesel air heaters. Running fans to heat exchangers on this small of a system takes more space then its worth I think, unless I can get some real small “Heater core” style exchangers. Although, as im typing this it could work well if they’re small enough.

Let me know your thoughts, and insights with what you’ve done. Thanks!

 

[somewhereinusa]

That's pretty much what I have except I have 4 zones with a thermostat controlled pump on each zone (room). I also have a heater core style exchanger in each room. Driver area has original bus heater for defrost and two more heater cores directed at driver. When driving driver area is typically a cold spot because of lack of floor in the driver area.

 

[nikitis]

Do you think it will get hot enough for a water heater? Sure for the floor, but Not sure a water heater will get as hot as you want it with such a setup, especially going through a flat plate exchanger. You'll lose a good bit of heat efficiency from that exchange.

@somewhereinusa 's design is nice and is mainly for fan radiators and floor heaters. Would this even work for a water heater? I don't know which is why I'm asking, but I would think it'd only get warm at best but I could be wrong on this topic.

 

[Crlefley]

@somewhereintheusa I did extensive reading on some posts with you describing your setup. Mine will be a bit simpler. One question for you, did you lay it into the floor with sleepers? I’m thinking of going 1/2 into the foam (i have 3in xps) and then laying 5/8 over it as opposed to 3/4. I suppose it doesn’t matter all that much what the sub flooring is. My piping will mainly be in walkway areas.

@nikitis It wont be full time hot water, but my plan is to have a tank, say 5-10 gallons in a dual hot water setup. So say a 120v marine water heater with a second heat exchanger input for the diesel heater to run. Example:
Engine off, burner running, cycling hot water through to heat water/engine.
Engine on, burner off, cycling through heat from engine coolant heat.
Engine off, burner off, 120v switched on to heat water.

 

[nikitis]

I guess the question is, how hot will the liquid traveling through the flat hot plate be in the end? This is unknown to me. I'd hate for you to go through this and it not be hot enough.

Also with this setup for hot water, you'd have to run the engine while sitting to heat your water wouldn't you?

Idle engine runs aren't good for it as the oil hasn't gone everywhere on a cold start, and will wear it out faster.

 

[Crlefley]

I guess the question is, how hot will the liquid traveling through the flat hot plate be in the end? This is unknown to me. I'd hate for you to go through this and it not be hot enough.

Right. I think I’ll do 5/8 subfloor. Flat plate exchanger will only be in use when Bus is running, which will be the heat source.

Also with this setup for hot water, you'd have to run the engine while sitting to heat your water wouldn't you?

No… that’s what the hydronic pump will do when the engine is off.

Idle engine runs aren't good for it as the oil hasn't gone everywhere on a cold start, and will wear it out

Right! So the idea would be to turn the valve on for the heat exchanger before starting the engine, and take the heat from the hydronic system to preheat the engine coolant.
I know how well that works, as I have on on each of my diese Volkswagens. (Frostheaters).

 

[nikitis]

Hrm.. Okay, sounds like you know what you are doing with it. I haven't seen anyone really do this yet to your degree, so I'm all ears watching how it turns out.

 

[Crlefley]

Hrm.. Okay, sounds like you know what you are doing with it. I haven't seen anyone really do this yet to your degree, so I'm all ears watching how it turns out.

Me too. I guess it will be a trial, and hopefully not by error!

 

[somewhereinusa]

There are a lot of pictures here.Hydronic heat
I use a marine water heater that has a built in heat exchanger. I tapped into the boiler wiring so that I can run it's water pump when the engine is running. The small heaters have their own switch for the fan. Except for the driver heaters I rarely have the rest on after initial warm up. They also have a temperature snap switch for each one so it won't blow cold air unless the water temp is high enough to make heat.

 

[Crlefley]

There are a lot of pictures here.Hydronic heat

So based on what I’m seeing there, it looks like you framed your insulated floor portion inside of some sleepers if you will, that are fastened to the bus floor?
Your zones aren’t massive, mine won’t be either.
Now you’ve got me thinking about your switch/temp setup. I also noticed your top flooring looks sectioned out, what did you put down? I decided to use 3/4 osb (the heavy stuff). I wonder if I could router that out for pex and lay lvp of sorts on it? With aluminum conductor of course. Otherwise, route out the insulation (osb is not glued down yet until post roof raise).

Thoughts?

 

[Crlefley]

I found this on the ole interwebs… looks to me like osb is suitable for putting pex into… maybe that’s my move? Router in some slots in the center. I doubt the osb will flex over time considering xps250 is under it?

Above Floor / Sleepers Installation | | DIY Radiant Floor Heating | Radiant Floor Company

Many people with an existing, non-radiant slab would like to enjoy the benefits of radiant heat, but don't want to jackhammer their floor, haul away tons of concrete, and re-pour a new radiant slab. Can't say I blame them. The solution is a new suspended slab, of course, and one of the...

www.radiantcompany.com

 

[somewhereinusa]

Top flooring is basically a floating floor. It's 3/4 inch plywood with H sections of aluminum between them. Plywood has some sort of hard plastic coating on both sides. I'm not a fan of osb for anything. I don't think it would be thick enough to route the grooves in. If I remember, it's been over ten years, I routed the grooves in the Styrofoam about an inch deep to accommodate the aluminum and 1/2 inch pex. Be sure to get the pex made for heating systems.

 

[Crlefley]

Top flooring is basically a floating floor. It's 3/4 inch plywood with H sections of aluminum between them. Plywood has some sort of hard plastic coating on both sides. I'm not a fan of osb for anything. I don't think it would be thick enough to route the grooves in. If I remember, it's been over ten years, I routed the grooves in the Styrofoam about an inch deep to accommodate the aluminum and 1/2 inch pex. Be sure to get the pex made for heating systems.

I see. Yeah the top layer is floating of course. IF the osb is 3/4 and The underlayment fins they sell on bezos.com (amazon) are thin, I would think one could get away with it. Router in a 1/2 inch slot, or maybe a 5/8 depth cut, and then staple the fins in to reflect the heat. Shoot, worse comes to worse, I just router down into the xps through the osb after it’s glued/fastened. I do intend to run some through bolts down through the bus floor to secure the top sheets. The floor wont be officially “floating” but I will have some added assurance that nothing will move.

 

[fishe160]

Hi, I never see these posts until the digest comes out, maybe this reply is too late for you. But anyways...
Our bus isn't done yet, so I can't say for sure this works, but its what we did.

In my research I found some of the following useful and also referenced @somewhereinusa.

idronics™

A journal of design innovation

www.caleffi.com

(A wealth of hydronics information, more than I had time to read)
Specifically, this one: 12 - HYDRONIC FUNDAMENTALS
It's got a lot of nice photos like this, with smart words to back it up

Radiant Floor Heating Installation Manuals
(recommended by a different forum member, I ended up buying a kit from them)

I ended up doing 4 layers: 2" XPS glued to the steel, 1.5" XPS with 2x3 sleepers glued down to that and attached to the side of the bus, 3/4" advantec tongue and groove subfloor and (TBD LVP).
The 2x3's are spaced for the edges of the ~4' sheet of plywood to screw down into, which is roughly every 16''. I put the pex 8" on center, so it meshed up pretty well between the sleepers. (A 5" bend radius for the pex is the requirement, but he told me I could go to 4" if its supported for the entire curve, which the foam does, to prevent kinks)
Since 1/2'' pex is 5/8" OD I started with that size router bit, but with the emissions plate and the wood the pex didn't fit, so I went 3/4" wide and 3/4" deep everywhere, it worked out pretty good.
Pictures explain everything better than my ramblings.


I attached the parts list from radiantec if it helps. He wasn't concerned about the heat moving through the pex, to the aluminum plate, to the advantec and vinyl plank flooring.

As far as the temperatures and what not, it gets a little confusing. The engine gets hot 200degF+, but your radiant floor will only want a max of 120-140degF to not damage it. Your DHW falls in the same range as the floor, so that's convenient. The pex melts at the engine temperatures. A boiler is hot as well.

So you end up with something called primary secondary, where there's 2 loops that share a common point, and it kind of works like a transmission where the radiant only takes a smaller flow and has a mixing valve to drop the temp if needed. It can be a thermostatic mixing valve (luxury) or a valve you very carefully adjust, and assume everything stays constant forever.
Somewhere's primary is on the left, and the secondary's are on the right in his drawing.
Another example from the fundamentals pdf:

It really is an art, and every application is unique.
Cheers!

edited for some surprise emoji's

 

[Crlefley]

It really is an art, and every application is unique.
Cheers!

Holy smokes, This is amazing information. Thank you so SO MUCH! So, You went with the sleepers in there to attach the subfloor to. Interesting. Ive already got 3inches glued down (XPS) and haven’t glued my 3/4 osb yet. I’m wondering if I could router out spots for smaller sleepers, or if the sleepers are necessary.

****, I even considered laying the pex in the 3/4 osb and then LVP flooring straight over that.
Now to do some thinking.

 

[Crlefley]

These are just further thoughts for me, but really, I could get away with some 1” XPs and sleepers to make it work. It would barely be enough, but then slapping 3/4 sub floor on that would make less of an issue for me. Your roof raise looks high @fishe160, where mine is only 14”. So I can only go up so much.

Again back to my thoughts.

 

[nikitis]

You should be fine with 3in especially since you roof raised it. I only raised 12in and have 4in XPS so even smaller than you and still have 7in over my head. I'm 5'11. I wouldn't worry about it

 

[Crlefley]

You should be fine with 3in especially since you roof raised it. I only raised 12in and have 4in XPS so even smaller than you and still have 7in over my head. I'm 5'11. I wouldn't worry about it

Right, but being I already glued the 3in down, If I built out sleepers like fishe, I would need another layer of 1 inch maybe? unless I router in all the slots for the sleepers in the existing 3 inch?

 

[fishe160]

Shoot, sorry I didn't post earlier.
I don't really know what I'm doing, so take it with a grain of salt. I think the reason I chose the sleepers was to try to follow the instructions of the T&G subfloor, and because I didn't have the confidence to glue the board over the PEX, and maybe trying to avoid putting things in a less than ideal spot, like under a wall, and can I get to it if I put a screw into it by accident. And there was probably a few other reasons the day of... Lol

You're right, our raise was excessive at 20", but we're tall people. Even with that extra room, I feel like I fight for every 1/16".

Kind of along your routing into osb comment, check out this page from the company:

Installing Tubing Within a Subfloor

Learn how to install radiant heating on top of a subfloor. This works well when you cannot access the floor from below. Let us show you how.

www.radiantec.com

I did this at the back for a small section that didn't need as much head room, it ended up being
Glue: 2" foam, 1.5" foam, 3/4 subfloor. Screw: 3/4" PEX and subfloor, .5" ply on top.

It was way easier routing through the foam, but this method might work to save you some space. I'm not sure if I would skip a top layer, and it seems like I'd want a full layer on the bottom, meaning, full sheet, PEX layer, full sheet. What thickness? I couldn't say.

 

[Crlefley]

Shoot, sorry I didn't post earlier.
I don't really know what I'm doing, so take it with a grain of salt. I think the reason I chose the sleepers was to try to follow the instructions of the T&G subfloor, and because I didn't have the confidence to glue the board over the PEX, and maybe trying to avoid putting things in a less than ideal spot, like under a wall, and can I get to it if I put a screw into it by accident. And there was probably a few other reasons the day of... Lol

You're right, our raise was excessive at 20", but we're tall people. Even with that extra room, I feel like I fight for every 1/16".

Kind of along your routing into osb comment, check out this page from the company:

Installing Tubing Within a Subfloor

Learn how to install radiant heating on top of a subfloor. This works well when you cannot access the floor from below. Let us show you how.

www.radiantec.com

I did this at the back for a small section that didn't need as much head room, it ended up being
Glue: 2" foam, 1.5" foam, 3/4 subfloor. Screw: 3/4" PEX and subfloor, .5" ply on top.

It was way easier routing through the foam, but this method might work to save you some space. I'm not sure if I would skip a top layer, and it seems like I'd want a full layer on the bottom, meaning, full sheet, PEX layer, full sheet. What thickness? I couldn't say

I See, So youre saying that for the rear, you did the 3/4 subfloor, and then screwed the pex too that subfloor sheet and did half inchply on top? Interesting. What kinda support did you do?

At this point im considering just routering out the foam, and maybe installing some brackets on either side of the plywood sheets to fasten them to the side of the bus chair rail. Otherwise, I would likely do the 1inch foam, and some 1 inch sleepers. Would be even cooler if I put a thin layer of aluminium between the two insulation layers to reflect the entirety of the pex (considering im routering out the 1 inch foam at that point, I could have two thermal deflectors.) Who knows. Interested in your pictures of the rear setup if you have any.