Calculation insulation thickness external water pipes?

[DC]

"Sharp" problem whose solution is CRUCIAL for me!

How to determine the thickness of one or more combined thermal insulators to bring the temperature of cold sanitary water (copper pipe diam 15 and 22 mm) above 0 ° c in an unheated room where the temperature would be in winter by expl of -5 ° C?

What technical data and which formulas to apply?

Thank you for your suggestions, it is urgent to build my pipe protection box before the bad season!

I am thinking of 18 mm plywood walls lined with a plate (thickness ??) expanded polystyrene (less dense frigolite) or polyurethane (denser = less insulating and more expensive ??).
Inside glass wool and polyethylene climatubes on all pipes.

Is it better to leave the hot water pipe to the radiators GLUTEN climatube?

In the same vein, a French window double glazing insulates as well or not as what thickness of a wooden door?

DC

[Christophe]

Drop the formwork! Pipe insulation will suffice ... IMHO!

But no insulator will maintain a frost-free pipe durably nor will it heat it (except using the latent heat of water)! It only delays the deadline!

An insulated pipe (1cm thick) where water circulates continuously will never freeze (except in Siberia). In short: it all depends on the flow!

A water pipe freezes when the water is not flowing!

So in your case, for the EFS, there will be a fairly regular flow unless the second home (in this case very specific I think there is only the solution of the thermostat and heating wire ... or the one drip ... see solution below)

We have a subject dedicated to the problem: put water pipes out of frost : https://www.econologie.com/forums/comment-ma ... t9062.html

You can read:

it seems that for -2 or -3, a simple drip a little big is enough to protect. to tell the truth, i never checked.

Description according to LM:

The anti-frost valve protects 25 to 50 meters of pipes against frost - When the temperature drops below 1 ° C, the valve opens and allows the water to flow. Thus the water coming from the hottest parts upstream of the circuit raises the temperature preventing frost. From 4 ° C the valve closes - Positioned at the end of the watering, heating and all other pipes exposed to frost.



Ref. : 66052266
Indicated price :
48.40 €

In short: 1cm of insulation + this valve = no problem!

[dedeleco]

It all depends on the detailed distribution of T in the room (buried or not, etc.), how it cools (outside air flow or total lack of insulation without any contact with the ground which brings heat above 0 ° C) and also the residual water flow in the pipeline to be adapted to its insulation and length.

This can be calculated simply for orders of magnitude, once the configuration is known.

Personal case, poorly insulated garage (draft under door) which drops well below zero by -18 ° C outside, does not freeze a stationary water pipe (closed sprinkler) in contact with house wall (brick) and foundation soil at 50cm, provided that I insulate the pipe with paper, cardboard and cloth on 5cm against the wall, because the heat of the ground goes up enough towards the pipe then to avoid freezing.

So the solution with still water is to promote contact with warm ground (10 to 13 ° C at 1m deep) or a warm house wall, strongly isolating cold air from the room. (heat flux coming from -5 ° C to make it much lower than that coming from the ground or the wall, it hot)

So it all depends on the precise configuration.

Under ground at -60cm in the Paris region, nothing freezes !!
Just take advantage of this heat that comes out of the ground, with a calculable heat flow !!
A layer of insulation 20 to 40 times thinner than the layer of earth or wall gives the same heat flux for the same difference in T !!
file: /// C: /Scapbook+0/data/20110728005401/index.html
http://fr.wikipedia.org/wiki/Liste_des_ ... thermiques
A metal bar of aluminum (6600 times more conductive than a fixed air insulator), copper, or iron (1500 times more conductive than a fixed air insulator) (therefore larger) planted in the ground deep can bring back enough heat to keep the pipe hot above zero if it is sufficiently insulated.
The dimensions must be calculated according to the expected T.

Similarly, a double glazed French window insulates as well or not as how thick a wooden door?

On wikipedia simple glazing insulates like 1 cm of air and double 2cm of air roughly rough at best, to fix ideas.
Wood conducts 4 to 5 times more heat than air and therefore it takes 4 to 5 times more wood thickness than air is about 4 cm (depends on the wood and the direction of the fibers) (very coarse, so a few cm).

[PITMIX]

Hello
A pipe must be kept frost-free by burying it more than 80cm underground.
To obtain the equivalent with insulation, you would need at least 1cm of foam and a self-regulating electric heating cord.

[Christophe]

Yes, but apart from in cave houses, the "internal" water pipes in the house are rarely buried ... are they?
By cons they can pass into the crawlspace.

Here; Questions.

How does the temperature of a crawl space evolve in relation to the outdoor T °? If it is ventilated? If it is not ventilated?

With us we have an unventilated vacuum (in the cellar) with water pipes to an indoor tap that is rarely used and they have never frozen.

A ventilated vacuum is more likely to freeze I presume ...

To come back to the subject's answer: I think that 1cm of insulation (standard insulation tubes for tubes sold in bricos) and a well placed frost protection valve will prevent any risk!

[dedeleco]

It is necessary to evaluate the heat fluxes from the ground (earth at 10 to 13 ° C at 40cm below) in relation to the cooling flux, losses from external walls or drafts.
In general, the floor under a slab gives lots of summer memory warmth, which is enough to keep it frost-free, except large heat leaks from ultra-thin walls and large air flow at -18 ° C !!

A bar of good section (to be calculated according to conditions) buried or sunk 50 cm underground is enough to bring enough heat to replace the heating cord around the insulated pipe a few cm of still air insulation, EPS, paper, cloth, cardboard, etc.,

[DC]

Thank you for your super fast reactions, I feel less alone!

The location of the pipeline is non-negotiable" at the upper corner of the ceiling (1,75 m from the ground) and of the stone foundation wall under the terrace (reinforced concrete slab resting on warps, total thickness +/- 25 cm) exposed west (shelter similar to a vacuum not ventilated, no air circulation as soon as the door and the window are placed).
This unheated room is below ground level for 3 of the walls, the last gives access by an embankment and a main bay (1.79 x 0.97 m) + accessory bay (0.91 x 0.46 m) drilled in a concrete wall (thickness 0.40 m).

I plan to place a glass door if I find (double glazing) or wood (lined internally with 4 cm of Frigolite) + a double glazing window in the accessory bay (or condemned by a wooden panel lined with insulation like the door) .

The pipes are 4.55 m long, with 1 "T" at the entry of the heating pipes in the room under the terrace (T for the temporary departure through the concrete slab to the radiators of the veranda that I hope to install on the terrace next summer) and an elbow at the exit to cross in the opposite direction at the other end of the foundation wall towards the shelter under the kitchen (fittings welded with hard Cu / Cu solder). For sanitary cold water, an elbow at each end.

So much for the data! For the form, I am curious to know the calculations of dedeleco I had to read it twice because the information is so dense and technical!

In winter, it is possible that the oil heating will be cut for 2 weeks in my absence (-> purge the entire DC circuit ??) or positioned on "antifreeze" (or idle speed, I don't know if that exists, the boiler is not yet installed ...), therefore the water will be immobilized in the sanitary water pipes (copper 15 + 22 mm) and in those of the central heating (2 x 22 mm) or at least very slowed down.

Isolation + an antifreeze valve (drip) placed at the end of the sanitary pipe or heating cord?

Where to place the antifreeze valves on the domestic water pipes knowing that one of the domestic water pipes is used to supply the propane water heater (15 mm) and the other (22 mm) to supply all the cold water intakes in the house ?

On these pipes, after crossing the retaining wall under the terrace, I placed a stop valve with drain valve which allows to stop the circulation of water downstream to the water heater or the rest of the EFS circuit and purge the downstream circuit.

Just before the stop / purge valve on a bypass (bypass of the pipe)?
The solution would then be to close the shut-off valve so to divert water into the bypass and let the drip flow through the antifreeze valve to the discharge line which, luckily, is nearby?

At this level the pipes travel with the others under the kitchen in a room also unheated and partially below ground level but currently better insulated because closed by doors and a small window (single glazing). The water has never frozen there since I occupied the house.

That said, the drip, I know (flushing the toilet that leaks ...), it is heavy without being aware of it day after day (here winter never lasts very long and the T ° rarely drops below -10 ° C so the loss will be limited if it is a real drip and not a consequent lost flow.

I believe that the most convenient solution is the heating cable "Self-regulating" even at 10 Eur / m.
I inquire about the placement (on each pipe individually?), The connection to the sector and the current consumption.
According to Orthosis, it can be cut to the desired length, the wire heats only in cold places and stops heating as soon as it reaches its temperature. It is both a probe and a heating element over its entire length.

Box simply in plywood and no glass wool in it to embed the pipes and "self-regulating" heating cord on the EFS pipes 15 and 22 mm. The quick fix ???

Does anyone have experience on this (I sent an MP to Forthose, thank you Christophe for the link)?

Thanks again for your experience solutions!

DC

[DC]

It is necessary to evaluate the heat fluxes from the ground (earth at 10 to 13 ° C at 40cm below) in relation to the cooling flux, losses from external walls or drafts.
In general, the floor under a slab gives lots of summer memory warmth, which is enough to keep it frost-free, except large heat leaks from ultra-thin walls and large air flow at -18 ° C !!

A bar of good section (to be calculated according to conditions) buried or sunk 50 cm underground is enough to bring enough heat to replace the heating cord around the insulated pipe a few cm of still air insulation, EPS, paper, cloth, cardboard, etc.,

I do not quite understand how to connect the buried bar and the copper pipes covered with climatube or embedded in a thermal insulator in a plywood box?
Connect the bar to a copper braid and wrap it around the copper pipes in the box? Insulate the braid itself by a sheath until it goes up to the ceiling ??

Thank you for everything !

DC

[dedeleco]

A priori this method is good with a good heat conductor (metal of sufficient section, function of precise details) well isolated from all that cools, tubes, bars, junction (braid, screw or welding).

duct until it goes up to the ceiling ??

is too vague on the exact geometry, which fixes the heat losses and flows, which can require several earth bars bringing the deep heat retained from summer to winter, if the pipeline is very long.

It also depends on your region and its climate and on the unheated room, cooled how, with drafts or not and how much minimum T outside over how long ????

If we want to be sure, we must calculate the heat fluxes in order of magnitude: (thermal conductivity) x sectionx (difference of T) / length (or thickness).
The bar must bring more heat flow than lost through the insulation (it has a large surface area and is thin but has low conductivity)

[dedeleco]

This unheated room is below ground level for 3 of the walls,

This fairly heavily buried cellar should never freeze (at least in the Paris region, personal case of a less buried basement, not freezing at -18 ° C outside, with inside mini at 4 ° C to 6 ° C and where I do not worry for 12 years, even absent) if without ventilation of cold outside air.
Indeed, the heat flow from the beautiful surface soil is enough to put out frost, because this flow is greater than the losses by the few non-buried walls (to be specified on the surface).