Air in domestic hot water system

[Marnhullman]

Background:

The cold water feed for my house has been taken from a mains supply that is 300 yards distant. The pipe runs slightly uphill for the first 150 yards and then downwards to my property for the next 150 yards. The house is at the same level as the mains i.e. there's just a small hill in between.

There is a pressure gauge incorporating a non-return valve immediately after the mains stop cock in the house.

The heating is provided by an oil fired pressurised system with an OSO hot water cylinder. There is a pressure reducing valve, set to 2.1 bar, also incorporating a non-return valve in the cold water feed immediately adjacent to, the OSO cylinder.

An electronic water conditioner has been fitted, due to the hardness of the water supply, although there's not much evidence, so far, of its effectiveness.

I'm told there are water pressure surges in the mains supply and a friend says that air gets into the supply sometimes - this is all anecdotal.

Problems:

1. Occasionally, there is severe water hammer in some of the hot taps when they are opened. It doesn't happen every time and I can't predict when it will occur.

2. Occasionally, there is a very loud scream from the pressure reducing valve next to the OSO cylinder. This happens when a hot tap is opened and cold water flows through the valve to top up the cylinder. As above it doesn't happen every time and I can't predict when it will occur.

3. There is always a whistling sound from the shower when hot water gets to the shower head, it doesn't start as soon as the shower valve is opened just when the water gets hot.

4. Hot water appears milky when it is first run into a basin, but it clears soon afterwards (I'm told this is a indication of air in the water?).

A local plumber and heating engineer has suggested a couple of things I could try to eliminate the problems but I'd like more advice before I invest time and money.

a) Remove the non-return valve adjacent to the mains stop cock to ensure there's no space (?) in the cold water supply. I'd actually have to remove the water pressure gauge as well but since I don't feel the need to regularly check the pressure I guess that wouldn't be an issue.

b) install a surge protection valve in place of the non-return valve removed in a) above.

Grateful for any comments/advice.

 

[Andy1946]

I may be shooting in the dark, but a couple of ideas have come to mind for you:-

1) Put pressure reducer in the line, near to the house (or in) as possible. Set to say 2 bar (about 28lbs/Sq.Inch)....as a starting level, see if all the taps run as fast as you need them to, especially upstairs. Adjust for best results. Knowing the pressure that you have now will help a lot in setting this up......

2) You sound as though you need an automatic air release or whatever they are called in the UK, on the mains, before the pressure reducer. One can easily make one if you cannot find anything local....ask me if you want to know exactly.

3)a) It is possible that you have your heating set to give water that is far hotter than need be, you did not mention if you had hot water storage or not, by the sound of what you are saying I would guess that is a "not", which is best anyway.....as storing of large quantities of hot water, no matter how well insulated is simply wasteful....especially at the cost of energy today and it will not get any better I am sure!! Keeping the temperature down reduces the amount of calcium that heaves the water and settles in pipes etc..(without a working water softener installed of course!)

3)b)What temperature do you run your heating at? If above 65°C, this is either an indication that the system is simply too small for the house, or the radiators have been badly sized, or your house is badly insulated/has a lot of serious air leaks......or the wife airs the house for too long at a time and too often!!(Joke!) Stop eating the beans!!! Try a lower temperature and see if the heating is warm and quick enough for you....

Water for washing bathing only really needs to be between 55 - 60°C max and some would say that is too high, I would not disagree with that comment either. Even 60°C is too hot for small children in a house I feel!

I would also suggest temperature controlled mixed taps for the bath/shower as if someone else uses the toilet, it can he a "hot" experience for someone under the shower!! (Mixer taps on all hand basins allows you to wash your hands under running water of about the right temperature, without using the plug and filling the basin. Done quickly, you will save on water usage!)

I have never understood why so many people in the UK like separate hot and cold water taps......

Its quite easy to check if your softener is working or not, mix some washing up liquid to make say a 20% solution with distilled water (20% washing up liquid to 80% distilled water. I have not done this for many years, so you might have to juggle the amounts a bit to get a test solution that is not too strong. The reason being that washing up liquid is generally very "strong" and it makes therefore exact measurement more difficult )

Make up say 1/2 pint of so for future testing.....

Take a set exact small set quantity of the water to be tested (start with say exactly 20cc in a seethru glass jar that is clean. Use some sort of kitchen measuring system) and add say 5 drops of the solution, shake the jar with the water to be tested and the 5 drops of solution and look for foaming. Keep adding say 5 drops at a time and shaking each time well before looking for foam. When foam is visible, stop instantly and count the total number of drops you added. The less the number of drops of the solution needed to make foam, the less calcium you have in your water. Its that simple.....

(Do remember that Iron can also stop water foaming, but you see iron stains in the bath usually.....I have not tested iron water in this way, but it may also work....!)

Do the same for a sample of water from before the water softener, it should take far more drops of your solution, showing that the softener is working and doing its job. Pure soap liquid from the chemists is more accurate, but washing up liquid works too if suitably watered down.

Make sure that the volumes of water tested are exactly the same each time, so that results are comparable with each other....make sure that your solution is kept in a sealed jar to stop evaporation.....

One tap in the kitchen should have untreated water as the body needs calcium and it has been said that people in soft water areas have more heart attacks!!! How true that is I cannot say.....

There used to be small water hardness tests kits that you could buy from a good chemist years ago for a few pounds in the UK which did exactly the same thing, but exactly and would tell you the degree of hardness!!

Copy the following link into your browser and search for similar kits in your own country:-

http://www.labwater.com/shopdisplayproducts.asp?id=164&cat=Hard+Water+Testing

 

[Marnhullman]

Andy

Thanks - the system does have a hot water storage cylinder and the water temperature is pretty high - I will reduce it.

BTW the device fitted is an electronic water conditioner - not a softener. Two thin cables are wound round the water pipe and connected to the device which, the makers claim, produces an electric charge that stops the calcium sticking to the pipes. It doesn't actually soften the water. So thanks for the advice as to how to test water hardness but it does not apply for my system (I do have a testing kit!)

I'll look out for an air pressure release valve but I'd appreciate your instructions on how to make one.

Regards

 

[Andy1946]

You need a spot on the pipe where you can add a vertical tube, as wide as you can get, 22mm being the minimum, which will tend to collect most, probably not all, of the air in the water in it.

It should be on the house side of the reducer if you install one. Or at the top of your hill where air will start to leave the water because of the lower pressure in that area....

Years ago I used to put a radiator bleeder valve at the top and bleed the air off occasionally by hand, but today, for very little money, you can buy them in automatic versions for rads, saves having to remember.

Should be good for up to 6 bar or so according to the ones I recently bought for our upstairs rads.....

The only other method which is slightly more complex to make is a "swirl pot", see this link (copy into your browser) for a car Swirl pot:-
http://www.grahamgoode.com/cool.htm#swirl

I made a diagram, included it in an album, but I have no idea how to get it into my reply, sorry!!!

I do not see this as a primary fix though, more of a last resort if you understand me.....

Sorry that I misunderstood about the water conditioner, I know now exactly what you have. I read the New scientist probably 25 years or more ago and they appeared to be of the opinion that they work. The only way I know of that you can tell is if you have say a furred up kettle, according to what I have heard, using the treated water, the kettle will lose its calcium over the following year with just being used......

Sorry, I have no idea otherwise on how to test if it is effective in changing the lime scale or not....

To test if the electronics are in order, I would imagine that bringing a small compass nearby might show something if very low speed pulses, otherwise a frequency counter with an aerial probe might show something.....or a small radio tunes to the Medium or long wave Band might give a tone out which switching on and off the unit will prove quickly if its coming from the unit or not....just an idea......[/img]

 

[Marnhullman]

Andy

Thanks for the follow up.

I've reduced the pressure to 3.0 bar and will wait to see if it stops the 'screaming' from the pressure limiter near the cylinder. Not too confident as the problem did occur when it was at that pressure previously - I increased the pressure because there was insufficient when using a hose pipe. Anyway it may help.

Will investigate the possibility of a surge limiter and an air vent.

Regards

 

[Andy1946]

Put your hose take off before the limiter, even if you have to move the limiter, that way you get the best of both worlds, but make a test first to see if it helps or not with regard to the screaming!!!!