Fitting hydronics after you have built your home « Alternative Technology Assn Forums

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Fitting hydronics after you have built your home

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Started 7 years ago by Marty50
Latest reply from Oilburner

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Marty50
Member

I'm looking at retrofitting hydronics to one room in my existing home. The room has cork tiles on a concrete slab floor which I would strip off.

The concept is to lay a new sprung floor in say timber but on top of something to contain the pex tubing. I found this site in the US which would simplify the job.
http://www.hydronicheating.com/

But otherwise I was thinking a series of battens or rout out some particle board myself.

It raises a whole raft of other issues though such as can most of the commercial timber floors be heated?

And before anyone ask why I am proposing hydronics tube rather than that thin electrical mesh and heat it from solar PV I am hoping up the track to send chilled water through the tube in summer generated from the same solar vacuum heat tubes that will provide hot water in winter.

Early days for the concept in my head but I would love to leverage off anyone elses experience.

Posted Monday 28 Apr 2014 @ 12:07:15 pm from IP #
munter
Member

I am just commissioning our solar floor now. Our hydronics are cast into the slab though so I can't offer any advice there. American websites may have more on how a hydronic system could work with timber floors.

Be aware that it is a fair bit of work to get a system like this working and plumbers (if you use them) are expensive. I also never found a technical consultant I could properly use to assist me so I have been working it out myself.

How is it you will get cold water from the evacuated tubes? Also, have you considered possible condensation issues if you were to cool the surface meaningfully?

Posted Monday 28 Apr 2014 @ 10:26:06 pm from IP #
Johnnojack
Member

Why not attach the piping to your bare concrete then lay a cement screed over it? You could then do a floating timber floor or tiles, tiles would work better for the heat transfer and if you have no cavity there will be no condensation.

Posted Monday 28 Apr 2014 @ 11:58:07 pm from IP #
axess
Member

Hi Marty50,

How about using a radiator instead of embedded tubing? The plumbing would be easier (albeit at a higher temperature 80C perhaps) and could you use the radiator as a chiller instead? There are lower temperature radiator systems around now I seem to have heard somewhere. Or you could use a skirting heater/cooler system instead perhaps as they run on a lower temperature. The chiller idea might need the coolth to fall from the ceiling to be more effective?

Posted Wednesday 30 Apr 2014 @ 11:16:55 am from IP #
gazmo88
Member

Or you could install hydronic pipes in the wall.

Quite common in Europe, but we found a company who do it here:
http://new.univenta.com.au/product/wall-heating/

No doubt there are other companies offering this stuff

Posted Wednesday 30 Apr 2014 @ 11:33:33 am from IP #
Marty50
Member

Gazmo, sounds like using a wall may be a good option after I have finished exploring all the floor options.

A professional hydronic installer told me that to concrete screed on top of my slab would require 40-50mm increase in height which would be unacceptable to me. But they only seem to use 16mm pipe in Australia whereas in the US they go down to 3/8 inch.

In terms of the timber I have found a local CNC router company that could make boards up for me but having problems getting information on timber. I want to know if heating and cooling may delaminate ply and if I cant avoid dew point when cooling will the moisture cause mould. The pool of knowledge on this seems to be small.

I found this interesting wall option. http://www.youtube.com/watch?v=2xVp7N0Vojk

Posted Thursday 1 May 2014 @ 12:58:06 am from IP #
Marty50
Member

Scored a bunch of hydronic radiators.

Posted Monday 5 May 2014 @ 11:58:58 am from IP #
Marty50
Member

Found a 130 liter hot water tank and wondering if it’s a bit small. Anyone able to confirm my calculations.

Posted Monday 5 May 2014 @ 12:02:26 pm from IP #
munter
Member

Re your calcs. The temperature differential you are using will be impossible to achieve in practice. The rate of heat transfer will decline as the temperature differential drops so you probably wouldn't want to wait for the water to drop to 20 degrees. I'm guessing 40 might be more realistic. You may also not get a whole tank starting at 90 when the return cold mixes in and cools down the remaining tank water.

For reference, I have a 400l tank for our 100m2 floor system. I'm not due it's big enough given the solar source I use I only available part time.

Posted Tuesday 6 May 2014 @ 9:52:00 am from IP #
axess
Member

Hi Marty,

135 litre storage gas hot water heaters have been used in the past to run small (1 or 2 rooms) hydronic panel systems.
There was an option at one time to add 1 or 2 small hydronic panels to an 200 litre Aquamax HWS to heat a bathroom or a small space as well as providing hot water. I can imagine both options would use a lot of gas to maintain even a 60 degree panel temperature.
What are you using to heat your water?

Posted Tuesday 6 May 2014 @ 12:22:23 pm from IP #
Marty50
Member

I'm looking at thirty low pressure vacuum tubes as a heat source. I'm hoping it will give me a reasonable temperature rise on a winters day which never really gets that cold here in Perth. I'm also hoping to eventually use the hot water in summer to run a chiller and pump cold water through the radiators. I'm going to pick the 135 liter tank up tomorrow.

Posted Tuesday 6 May 2014 @ 1:37:22 pm from IP #
Marty50
Member

I'm selling off the two largest hydronic radiators so I can afford to buy a new set of vacuum tubes if anyone is interested.

http://www.gumtree.com.au/m-my-ad.html?adId=1046247222

Posted Tuesday 13 May 2014 @ 1:02:02 pm from IP #
Marty50
Member

Tank refurbished. Now for some vacuum tubes.

Posted Tuesday 13 May 2014 @ 1:07:04 pm from IP #
Marty50
Member

Have ordered 30 vacuum tubes.

This is a diagram of the overall system.

Posted Friday 23 May 2014 @ 3:04:52 pm from IP #
karmacoma
Member

Wow, Marty, you drew that? Really interesting concept for a one-room hydronic system.

I could imagine using that for our one south-facing bedroom-cum-office. Although I had hydronic heating pipes (for gas-firing) laid throughout the house during our build, it turns out that the passive building design is taking care of heating the main living area. We don't really need to run the whole gas-fired shebang, except that that one constantly-used south-facing room is intolerably cold.

A little solar active system like yours shown here would deal with that cold south-facing room, and we'd live warm for free.

Yours is also a good concept for new builders to consider too as an alternative to a whole-house solar hydronic system, which is very big (both collectors and tank) and crazy expensive. This small design to deal with a specific cold room, teamed up with passive building design measures for the rest of the house is a great alternative technology.

I don't suppose you could share an equally well-laid-out sheet of sizing calculations for your proposed system?

Posted Friday 23 May 2014 @ 10:33:31 pm from IP #
Marty50
Member

Karmacoma, I haven't done much detailed calculation for the design, Relying on utilising components I have been lucky enough to come across doesn't lend itself to good design. But I will do some calculations and share when I have all my components together.I paid for the low pressure vacuum tubes this week so when they get here I will first be focusing on the best spot left on my roof to place them. Then I need to look at pump flows to get optimum winter heating into the tank size I ended up with. I'm also wondering if I can have the tank indoors to minimise heat loss. I think to shorten pipes its going to have to live outside. As soon as I have more I will post.

Posted Saturday 24 May 2014 @ 1:37:20 am from IP #
Marty50
Member

Have been experimenting with some control stuff for my system.

Posted Saturday 24 May 2014 @ 1:41:18 am from IP #
karmacoma
Member

Marty, some questions:

Why does the system need a header tank?
Any specific reason it connects to the radiator side?
What spec or make/model are the circulation pumps you're using?
What pipe type(s) are you using?
I guess you can outline the control hookup when you've got it working?

Ian

Posted Saturday 24 May 2014 @ 2:34:44 am from IP #
Marty50
Member

I'm using low pressure. This makes the vacuum tubes cheaper and some suggest that the low pressure tubes may be more efficient. Thus a header tank with a spill outlet should handle any expansion from the heating. It should merely flow back up the inlet pipe when the tank gets hot.

When the tank has been heated during the day I will pump hot water through the radiator circuit to warm the room.

The pumps I have sourced off eBay are various 24 volt DC types as I will be running completely free of mains. There is a supplier in Victoria I normally use and he told me last week he even has a completely stainless steel pump with built in MPPT which means you can connect directly to a solar PV. However I will be using a controller with differential sensors and running the pump off the 24 volt solar cooler batteries which are close by and don't get used in winter.

Yes there is a bit of suck it and see in this and I will detail it when I have it working. You can follow some of my projects on this link https://www.facebook.com/pages/Sustainability-Solutions/107425999363469?ref=bookmarks

Also I have a few articles in Renew magazine.

Posted Saturday 24 May 2014 @ 2:50:18 am from IP #
Marty50
Member

This is one of the pumps I am considering for this system. These can be obtained from China for around $22 and will work up to 100 deg C. I have used this pump in one other application and it is still working.

Posted Saturday 24 May 2014 @ 3:00:18 am from IP #
Marty50
Member

This is another pump I am considering for this system. They cost ~$80 and can be purchased in Australia. I have used this in the split solar HWS detailed in my Renew article. One of them failed because it was mounted incorrectly and the replacement failed when an O-ring leaked. I am on my third pump but the pump works harder in this application. I now keep a spare pump on hand so I don't run out of hot water.

Posted Saturday 24 May 2014 @ 3:05:08 am from IP #
karmacoma
Member

Lots happening there on your facebook page ... I don't get Renew mag so haven't seen any of your work. You're clearly determined and indefatigable. Wish you'd run a blog rather than FB, since FB is so disjointed. Anyhow, I'm glad you're copying in everything about your mini solar hydronic system on this forum. It's mighty interesting.

Posted Saturday 24 May 2014 @ 8:24:21 am from IP #
Greg
Member

Marty, I'd suggest you put the pump for the solar on the cold water side to pull the hot water through. If you hit stagnation it could get to 130C till the water circulates. I think this is where they are normally placed and should mean you never get really hot water passing through. I think you might also want to put a flow regulator next to the pump so you can vary the flow rate and hence heat exchange rate.
Are there heat exchangers in the tank or are you just using the standard cold in and hot out ?
What is the volume of the header tank? Can it take the additional volume of water created when the water expands due to heating? I'd estimate you might get about 5 litres due to expansion. If it won't I'd suggest an expansion tank on the cold water side.
What will you do with the system during summer ?

Posted Sunday 25 May 2014 @ 9:54:04 pm from IP #
Marty50
Member

Greg,
Thanks for your suggestion about placing the pumps at the cooler end of the tank. It’s something I was thinking about but clearly not when I did the sketch.

However I didn't think it was possible to super heat water unless it is contained so that there are no nucleation points where steam can form? I am not using heat exchangers in the tank and the header tank of 5 liters float valve and overflow. My expectation is that any expansion in such an open system should flow back through the cold inlet to the header tank on the cold side and be captured by another small container to be reused on the garden when it has cooled.

The pumps I am planning on using allow a range of voltage to be applied to them which adjusts their speed so I am hoping to build into the software control system (Arduino) a feedback loop that allows flow to be regulated by utilizing this feature of the pump.

I will likely empty the system during the next summer but have eventual plans to utilize the hot water for an adsorption chiller which I hope to construct.

Posted Monday 26 May 2014 @ 1:23:20 am from IP #
Marty50
Member

Greg,

Thanks for your suggestion about placing the pumps at the cooler end of the tank. It’s something I was thinking about but clearly not when I did the sketch.

However I didn't think it was possible to superheat water unless it is contained so that there are no nucleation points where steam can form? I am not using heat exchangers in the tank and the header tank, of 5 liters, contains a float valve and an overflow. My expectation is that any expansion in such an open system should flow back through the cold inlet to the header tank on the cold side and be captured by another small container to be reused on the garden when it has cooled.

The pumps I am planning on using allow a range of voltage to be applied to them which adjusts their speed so I am hoping to build into the software control system (Arduino) a feedback loop that allows flow to be regulated by utilizing this feature of the pump.

I will likely empty the system during the next summer but have eventual plans to utilize the hot water for an adsorption chiller which I hope to construct.

Posted Monday 26 May 2014 @ 1:25:02 am from IP #
karmacoma
Member

What would happen to a system like this if it wasn't emptied over summer, but the room heater had been turned off by the thermostat? Would something be spoiled or burst?

What would be the failsafe? Just the usual pressure valve on the HWS?

Ian

Posted Monday 26 May 2014 @ 7:36:10 am from IP #
Marty50
Member

I'm not planning on a pressure valve as the inlet pipe will be open to the air. Any pressure should force its way back up to the vented header tank and out the overflow. It probably won't harm to leave it filled during summer. I will just have a tank full of hot water and nothing to use it for until I build my chiller. Perhaps I should run it full during summer just to see how hot I can get it.

Posted Monday 26 May 2014 @ 8:25:14 am from IP #
Jimmy
Member

Marty, I think you're concept is good, one suggestion would be pipe work needs to be reconfigured.
For example, the hot water returning from the manifold needs to enter the storage cylinder at the bottom. Likewise the hot water needs to be entering the radiator at the bottom. A sensor could be fitted to de-activate the circulating pump to collectors when the collectors aren't harvesting solar energy.

Posted Wednesday 28 May 2014 @ 9:33:18 am from IP #
Marty50
Member

Posted Wednesday 28 May 2014 @ 10:16:48 am from IP #
Marty50
Member

Having problems posting images!

Posted Wednesday 28 May 2014 @ 10:18:49 am from IP #

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