Water drain-down

[Pete-B]

 

Hi, as anyone used the Floe system to drain down the water? It seems, looking on E bay and Amazon, that there are 2 or 3 different models.to choose from!

[armstrongpiper]

I use the Floe kit for Motorhomes with on board water tank. The Floe system works fine on the hot water side, using the reservoir of air in the boiler pressurised to 15psi. The cold water side is more problematic as there is no means of building up a similar air supply, and my compressor doesn't have the capacity to blow all the water out.

While typing this, it has just occurred to me that it may be possible to temporarily connect the cold water pipe into the boiler hot water outlet and then use the air reservoir as before. Something to look into tomorrow.

So far, I have resorted to connecting a spare bit of pipe to the cold supply and using my lung air reservoir to blow the water out.

 

Neil B

[pepe63xnotuse]

Mornin'..

 

Sorry Neil, I don't quite follow..

If the cold side is fully closed off, why won't it pressurize?

 

With our previous van, although I didn't have the actual Floe kit but I was able to easily access the main feed pipe, at the top of the on-board tank(under the dinette seating), disconnect it and then just pressurize the system from there.

 

It was surprising just how much water it shifted from a supposedly already fully drained down van..

[Derek Uzzell]

This 2011 forum thread may be of interest

 

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Diaphragm-water-pumps-/26046/

 

I agree with pepe63 - if the water system is ‘air pressurised' so that residual water can be expelled from the hot taps, I’d expect that water could be similarly expelled from the cold taps.

 

There is an inherent risk with this draining methodology that the system will be over-pressured, so care needs to be taken that this does not happen. I note that Floe now markets a product to avoid that possibility and simplify the draining procedure:

 

https://tinyurl.com/yc2vfxpe

[armstrongpiper]

What I was trying to explain is that one needs a certain amount of air to successfully blow the cold water out, and, on my van at least, there is no reservoir of air (as when blowing the hot water side). If one has a compressor which will supply sufficient air, rather than a weak 'puff' as with mine, then all is OK. My compressor is a budget one from our local car shop, but it does the tyres to 75psi given time.

I agree that there is a danger of over pressurising the boiler - one has to be vigilant!

 

Neil B

[pepe63xnotuse]

Hi again Neil...

'Still not clear, if I'm honest... :$

 

As you say, the "closed" system only has to be pressurized up to 15psi, before each tap is "flushed" through...so I can't see why that isn't also flushing each Cold tap through in turn?

 

..and it's not the air coming out from the compressor that's doing the "blowing" as such...it's the air that it's already pressurized, and being held, in the system..

..and once achieved, 15psi is the same, whether someone has got there using a budget pump , or a top of the range job. :-)

(ours was/is only a cheapish 12v pump)

 

(are you sure it(the Floe fitting)is spliced into the right line/position?)

 

 

 

 

[armstrongpiper]

The cold water system pressurises OK when the taps are closed.

I will explain the water system in my 'van (and it has been thus in other 'vans I have owned, but maybe yours is different) Starting at the tank, the pump draws water and delivers it to the boiler via a non-return valve. Before the water reaches the NRV it branches to the cold water side. Just after the pump is the branch for the Floe pressurising connection. Before attempting to blow residual water out of the pipes, one drains as much as possible via the boiler drain-down valve. When one blows air into the system you raise the boiler to 15 psi. Open hot water taps to blow water out, adding more air from the compressor as necessary. Open cold water taps and the NRV prevents air from the boiler flowing to the cold water pipes, hence the pressure left in the pump/pipes is very soon dissipated and no water is blown from the opened cold taps. The only air available to the cold side is that from the compressor, ie, not enough. Try it. So if one connects the cold pipes to the boiler hot outlet , one will then have enough air to clear the cold pipes.

I hope this is now clear enough.

 

 

Neil B

 

[Derek Uzzell]

Neil

 

With your motorhome’s water system (as I understand it to be) and where the Floe pressurising connection is, the draining procedure will behave as you have described.

 

If the water system is based around a diaphragm water pump and, consequently, should not need NRVs, the hot and cold water pipework should both pressurise adequately. I pretty sure pepe’s motorhome’s water system includes a diaphragm pump (both my prevous and current motorhome have that type of pump) so your cold water-related problem won’t arise.

[armstrongpiper]

There is an NRV at the inlet to the Boiler. If there wasn't, you would get hot water flowing from the Boiler to the cold pipes. hence, no air reservoir for blowing the cold pipes. I am speaking from experience.

I initially responded to a query from the OP on this thread, so hope he, at least, isn't confused.

 

Neil B

[Derek Uzzell]

How the Floe product will function will depend on the design (and ‘logic’) of the motorhome’s water system and where the Floe pressurising-valve is inserted.

 

This video-clip

 

 

shows the Floe system being used to clear residual water from a caravan’s pipework by pumping air into the caravan’s water inlet. This method pressurises both the hot and the cold pipework inside the caravan.

 

If a motorhome has a diaphragm water-pump, the Floe valve can be insertded in the water-pipe leading from the pump’s outlet and the pump itself will act as a non-return valve (NRV).

 

Alternatively (and I think this was what Floe used to suggest), the Floe valve can be inserted in the water pipe between the fresh-water tank and the diaphragm water-pump and an On/Off valve is then added between the fresh-water tank and the Floe valve. Prior to air being pumped through the Floe valve, the On/Off valve is closed.

 

If the motorhome has a submersible water-pump (ie. the pump is within the fresh-water tank), the Floe vave is inserted in the single water-pipe that leads from the fresh-water tank and that ‘feeds’ the rest of the motorhome’s water system. An On/Off valve is added between the fresh-water tank and the Floe valve and, prior to air being pumped through the Floe valve, the On/Off valve is closed.

 

In each of the above three cases, pumping air into the Floe valve causes the complete water system to be pressurised and allows water to be expelled from cold water-outlets as well as hot water-outlets.

 

I don’t really see why your IH600 has an NRV at the boiler’s inlet as, when the motorhome’s water-pump is operating, hot water won’t flow from the boiler to the cold water pipework as the pump will be pressurising the cold water-pipework as well as the hot water-pipework. Having said that, I’m not familiar with what IH does, so there may be a good reason for the NRV at the boiler (though I can’t actually think of one...)

 

In principle, if the Floe valve is inserted in the main water ‘feed’ pipe leading from the fresh-water tank (and an On/Off valve added before the Floe valve if required) it should be practicable to expel residual water from the cold taps as well as the hot taps.

 

As I’ve said in the past, I've pressurised my motorhomes’ water system via the shower hose (relying on the diaphragm water-pump to act as an NRV) and this allows residual water to be blown from the cold and hot pipework with the boiler acting as a sort of air reservoir.

[armstrongpiper]

My last contribution to this saga is - with the system fully filled and hot water in the boiler, but pump switched off, opening the hot tap gets a flow of hot water, proving the boiler has pressure. If the hot tap is closed and then the cold is opened, there is little or no water flow, cold or hot. this would then indicated the presence of an NRV.

I am now going to get my 'van ready for its first trip of the year to France/Italy, so won't have the time for further arguments.

 

Neil B

[dipsticks]

Draining your system.

 

Forget pressure, forget Floe. What is required is a large volume of fast flowing air, (open vented to atmosphere via the open taps so negligible pressure) for less than a fiver you can do this and get all the water out in a few seconds.

 

Just go to your local garage and use their high flow air supply (for tyre inflating) but make sure your taps are all open !!! Job done I have been doing this for 30 years and it works perfectly everry time.

 

I have fitted a tee piece adjacent to the pump in the inlet pipe with a stop valve behind it on the tank side. In the tee is a car tyre valve. To drain and evacuate the water from the pump and pipework I shut the stop valve, open all the taps in the van, switch on the pump then pressurise the valve with compressed air to blow all the water out of the pump and system. It works a treat.

 

Don't forget to drain the water heater and empty the tank, and of course open the stop valve at the start of next season.

[Derek Uzzell]

dipsticks

 

In 2011 (ref 1st link in my posting of 2 May 2018 8:59 AM above) when you described the arrangement shown in your photo and said that you "pressurise the valve with compressed air to blow all the water out of the pump and system”, I asked what you used to provide the compressed air. You did not answer that question at the time.

 

I’m doubtful that (realistically) many people would choose to drive their motorhome to a garage to use the latter’s compressed air supply. It’s much more likely that they will want to carry out the complete draining task in one go wherever the motorhome will be over-wintered.

 

It’s certainly true that resdual water can be expelled from a motorhome’s pipework without investing in a Floe system - my blowing-air-though the shower-hose ploy cost me nothing to implement and (as it happens) I have a high volume tyre-pump that can provide the “fast flowing air” you mention.

 

For the record, I note that Truma’s installation instructions for a “Combi” heater (which an IH Motorhomes 600S will have) say that when pressure pumps with a large switching hysteresis are being used, hot water can flow back via the cold water valve. In such cases it is recommended that a non-return valve (NRV) be installed between the outlet to the cold water valve and the safety/drain valve to prevent return flow. Similar advice was given for Truma C-Series appliances.

 

I’ve owned three motorhomes - two with Truma C-series heaters and one with a Truma Combi. SURflo diaphragm water-pumps were fitted to all three vehicles and none of them had the NRV Truma mentions. To the best of my knowledge, despite there being no NRV hot water never flowed back into the cold-water pipework.

 

However if an NRV is fitted where Truma suggest, expelling residual water from the cold-water pipework will be inhibited if (as Neil B has mentioned above) the volume of air being pumped into the pipework is small. So, if a motorhome has the NRV, to clear the cold-water pipework properly it will be necessary to use dipsticks’s ‘garage’ method or a ‘high-flow’ compressor.

 

[dipsticks]

Well done Derek, thanks very much for your very detailed posting, accurate as usual !

 

That's it then, to sum up:-

 

Upwards of fifty quid for a floe and all the messing around using it.

 

or

 

About a fiver for a few fittings and pop into a garage for 2 minutes on the way home from your last trip of the season.

 

or

 

Free if you have a pair of lungs like Derek's.

 

Realistically, the choice is yours.

[Brian Kirby]

I don't understand what the problem is. Why won't these systems drain satisfactorily by gravity? Is this a problem for certain vans only, because they have badly designed/installed water systems, or does the problem only arise with certain components or combinations of components? Why are airlines and even Floe systems (or human puff!) necessary in order to dispel every last drop of water from water systems? If the taps are opened with the pump off, both water heater and fresh water tank valves opened, and the van then taken for a short run, the amount of water remaining in the system should not present any risk for damage from ice. Is there something that I'm missing? I'd be grateful to know, in case it may affect our van.

[Keithl]

dipsticks - 2018-05-04 4:45 PM

 

That's it then, to sum up:-

 

A Upwards of fifty quid for a floe and all the messing around using it.

 

or

 

B About a fiver for a few fittings and pop into a garage for 2 minutes on the way home from your last trip of the season.

 

or

 

C Free if you have a pair of lungs like Derek's.

 

Realistically, the choice is yours.

 

Sorry but in my books, none of them!

 

A. My system drains fine on its own so save my fifty quid.

 

B. I would never blow garage forecourt air into my water system for fear of contamination. It may contain rusty water, oil or who knows what?

 

C. I would never blow with my mouth (or anyone else's mouth for that matter) for fear of bacterial contamination. Especially when you are then going to leave the system standing for weeks or even months.

 

My view for what it's worth and has been my principle for the last ten years or more without incidence.

 

Keith.

[dipsticks]

Keithl - 2018-05-04 8:25 PM

 

dipsticks - 2018-05-04 4:45 PM

 

That's it then, to sum up:-

 

A Upwards of fifty quid for a floe and all the messing around using it.

 

or

 

B About a fiver for a few fittings and pop into a garage for 2 minutes on the way home from your last trip of the season.

 

or

 

C Free if you have a pair of lungs like Derek's.

 

Realistically, the choice is yours.

 

Sorry but in my books, none of them!

 

A. My system drains fine on its own so save my fifty quid.

 

B. I would never blow garage forecourt air into my water system for fear of contamination. It may contain rusty water, oil or who knows what?

 

C. I would never blow with my mouth (or anyone else's mouth for that matter) for fear of bacterial contamination. Especially when you are then going to leave the system standing for weeks or even months.

 

My view for what it's worth and has been my principle for the last ten years or more without incidence.

 

Keith.

 

Fair comment Keith, you are very lucky to have a system that drains itself well, I'm impressed that such a system exists, I wonder how many drain points you have. I would'nt use the mouth method either and am surprised that, could be effective at all.

 

I sterilise my whole system at the start of every season and once again half way through so I feel confident that I am not contaminating myself ! Even minute amounts of residual water are likely to harbour bacterial growth. (even without the addition of garage air) Are you sure your plumbing is quite dry inside after draining itself ?

 

I would think that larger vehicles like yours and Brians are likely to incorporate better designed plumbing layouts than smaller PVC's like mine where the plumbing has to be compacted into smaller spaces thus less efficient self draining and therefore the need for assisted water evacuation.

[peterjl]

I must admit I have been wondering why there is so much fuss over draining the water system. We have a pvc and I drain at the end of each trip. Usually on the last morning I trip the water drain on the boiler, open the taps, and take out the water bung in the bottom of the fresh water tank.

I reckon that after this the drive home will shake out the minimal water left after the siphon effect has drained the system.

 

I have never had problems and certainly have never bothered sterilising my system. It’s never been a problem. Imagine that there may be the exception where the system is a problem but this should be the exception rather than the rule.

 

Peter

[Derek Uzzell]

I’m not exactly sure why it might be thought that I use ‘lung power’ to expel residual water from my motorhome’s water pipework. In the 2011 forum thread I provided a link to above I described the method I employ as follows:

 

"I have a gizmo that I bodged up from a 15mm brass plumbing compression fitting and a truck tyre-valve. I unscrew the shower head from the motorhome's shower hose and screw the gizmo into the end of the hose. Using a 12V tyre-pump I can then pressurise via the tyre-valve my Hobby's water system 'downstream' of the SHURflo pump. Subsequently, by opening the taps, residual water can be purged from the system. Because a SHURflo pump (when not running) acts as a non-return valve preventing water from passing in the outlet-to-inlet direction 'my' method of purging residual water does not require an additional stop-valve."

 

I owned a Herald motorhome for 6 years and - when winterising it - I never ‘blew’ air through its water pipework and the Herald never suffered any cold-weather-damage, After that I owned a Hobby motorhome for 9 years and during that period I began to use the ‘pressurised-air’ method as part of the winterisation process.

 

My Hobby’s water system included Comet’s “X-FIX” modular plastic manifolds (photo attached) and these could collect water remaining in the pipework despite the system having been very carefully drained down using conventional methods. This became evident after a very cold winter when - during reinstating the water system - I discovered that the elements of the most complex X-FIX manifold had been forced apart when water inside the manifold had frozen. To guard against this happening again I decided that, henceforth, I would use pressurised-air to remove from the pipework as much residual water as possible.

 

Relying on draining via gravity (with a bit of rough-road driving afterwards perhaps) may be sufficient to 100% protect a motorhome’s water system from frost-related damage, but the first time the pressurised-air method is employed it’s startling just how much water is expelled through the hot and cold water outlets and (in the case of my Hobby and Rapido) through the toilet’s flush outlet. Plainly, if the weather were cold enough, that water would have frozen. Whether that freezing had caused harm would only be discovered subsequently, but if the water has been removed from the motorhome’s water system during winterisation, the freezing risk will have been sidestepped.

[Pete-B]

 

Just how critical is it to use 15psi on the system? The reason I ask is, I've somehow acquired two 12 volt air compressors and two manual air pumps. If I inflate a tyre to say 35psi and then check with a gauge each of the four give a different reading!

[Derek Uzzell]

Floe’s website says:

 

"Touring caravans, motorhomes and boats

 

We have a number of kits available which are either fitted outside if you use an outside portable water tank, or fitted inside if you have an on-board tank. To drain down, first the water heater and on-board tank (if applicable) is drained and then the dump valves are turned off together with all the taps to seal the system. Floë is fitted to the vehicle and the compressor and the system is pressurised to 15 PSI. Once pressurised, the owner opens a tap inside, such as the hot kitchen tap. (Doing this will demonstrate that air is passing through the water heater). After the water is pushed out and only air is left, the owner turns off the tap again to reseal the system.”

 

I don’t know if Floe chose 15psi because it’s close to 1bar (14.5psi) or if it’s convenient to remember, but it’s certainly not critical to pressurise the water system to exactly 15psi.

 

A motorhome’s water system should comfortably be capable of being ‘air pressurised’ to 15psi as the vehicle’s own water-pump will produce a pressure above that during normal day-to-day use. The Floe concept is based on the water system being ‘sealed’ and then pressurised by air being blown into it. If the resultant pressure within the water system were too low (say, 5psi) then, when a tap was opened, residual water would not be adequately expelled. If the pressure were too high (say, 40psi) there’s a risk that the water system’s pipework/joints won’t have been designed to handle that pressure and might be damaged. So 15psi is a ‘happy medium’ compromise-pressure that should be risk free and still cause residual water to be efficiently expelled - but 13psi should be OK, and so should 17psi. If in doubt start low...

 

I have three 12V air compressors, but I don’t rely on any of their (analogue) gauges when checking/adjusting tyre pressures, as the gauges’ readouts vary from "somewhere near" (one compressor) to “hopelessly wrong” (the other two). But (because I have an accurate tyre pressure-gauge) I know what around 15psi equates to on the gauge of the compressor I use when pumping air into my motorhome’s water system, even though the needle on the compressor’s gauge is indicating a completely different pressure.

 

It needs to be emphasised that a degree of caution is needed when 'air-pressurising’ (however you do it) to ensure that the water system is not over-pressured. The method I use - pressurising the system via the shower-hose - obviously needs to have the shower’s water-outlet open to allow air to pass from the compressor through the hose and into the water system. Except I once forgot to open the shower-outlet when winterising my Hobby and, within seconds, the pressure in the shower-hose had rocketed, followed by a loud bang as the hose was blown clean off its threaded connection to the shower water-outlet. Surprisingly, neither the shower’s hose nor its water-outlet were damaged and, as the outlet was easily accessible, reattaching the hose presented no difficulty. It would have been another matter if that had happened with my current Rapido as the shower-outlet-to-shower-hose connection is concealed behind a large plastic moulding that’s not easily removable.

[dipsticks]

I'm just wondering how you get the water out of the pump itself and the piping between the pump and the first water outlet in your system Derek ?

 

Thank you.

[Derek Uzzell]

My Rapido has a SHURflo water-pump mounted on the top surface of the fresh-water tank beneath the rear bed. Water pick-up is via a simple pipe starting from a ‘dint’ in the water tank’s floor and ending at a strainer on the pump’s inlet.

 

The steps in my draining procedure are

 

Open the fresh-water tank’s drain-tap to empty the tank.

 

Run the water-pump to remove as much as possible of any water remaining in the tank.

 

Open all water outlets and Truma “Frost Control” safety/drain valve to ‘gravity drain’ the Truma Combi heater and the overall water system.

 

Close Frost Control valve and carry out ‘air pressurising’ process using the shower-hose, with the SHURflo pump acting as a non-return valve.

 

Close all water outlets.

 

Disconnect water-pipe from water-pump’s outlet and ‘air pressurise’ again to expel water remaining in that pipe.

 

Sponge out the tank via the two large ‘hatches’ in the tank’s top.

 

Run water-pump again. Remove pump’s strainer unit from pump’s inlet: empty, clean and dry strainer unit. Run pump again until it’s certain that there is no water remaining within the pump. Reattach strainer unit and reconnect water-pipe to pump’s outlet.

 

Open Frost Control valve and ensure all (mixer) water outlets are open and in centralised position.

 

It needs saying that the above procedure replicates what I used to do with my Hobby motorhome where the SHURflo pump was less accessible than the Rapido’s and I had different 12V compressors. It would be more logical, simpler and efficient with the Rapido to either follow your procedure and put an ON/Off valve and an ‘air pressurising’ valve in the pipe leading from the fresh-water tank to the water-pump, or to put an ‘air pressurising’ valve adjacent to the water-pump in the pipe leading from its outlet. I’ll investigate the latter option when I next drain down the water system.

[MartinP]

I too follow a thorough, meticulous, regime to drain our Autotrail Arapaho.The Shurflo pump is on the wall of the compartment under the wardrobe. It is not very easily accessible. I've used various methods to drain down and expel all the water before the weekday storage.

The first time i had a problem I had drained down the system but not blown it through. Friday morning , ready for a trip, found the pump was leaking from the head. Expensive.(£95) as it had to be sourced asap from a high street caravan store or similar bandit.

So then I started to drain down and blow out by various means.

 

When it happened again I was very "p"eed off to get caught again - when I had thoroughly drained down and blown through. Another pump - a bitter taste etc.

On investigating the system after blowing through, removing the filter etc I disconnected the pump and tipped it out. There was still, ~~15-25ml of water remaining.

That's the bit that freezes and destroys the head.

 

So now I blow through etc but as a final check I disconnect the JG fittings either side, remove three of the four pump mounting screws and swivel the pump to drain the dregs. It's a pain....But I always get some water out so it feels justified.!!

But I still end up muttering "Who designs a £70K motorhome with a system that has an inherent failure built in?......

[Derek Uzzell]

There’s nothing particularly novel about using pressurised air to remove residual water from a motorhome’s water system as part of a winterisation procedure.

 

My Rapido’s User Manual includes a complete chapter about ‘wintering’ the vehicle and - in the “Emptying of fresh water section" - is the advice that

 

“To ensure complete emptying, it is possible to blow air into the water circuit, in which case do not exceed 0.5bar”.

 

However, no information is provided as to how this might be done.

 

On a French motorhome forum ("Le camping car pour les nuls”) there is a 2013 entry reviewing the installation of a Floe kit. This invited a few comments, including one suggesting that using pressurised air was unnecessary as ‘gravity draining’ should be adequate, and another that blowing (ie. using ‘lung power’) through opened taps was a good idea.