Plumbing advice required...

[Azinat]

I have a pretty standard chauffe-eau setup.  Mains water supply has stopped in the house (frozen pipes outside) so no cold running water.  However, no hot either (the ballon was full).  Basically no hot will come out if there is no cold supply in (some sort of gravity system?). 

In normal use we need to keep hot tap open full and cold about 10% to have very warm water.  If we add any more cold, it will draw the supply away from the chauffe-eau and the hot water supply will reduce considerably.

Is there some form of valve that can be added to the system?

Thanks

[Dave&Olive]

if you have no cold supply then you will not get any hot water.Most hot water systems in France are unvented hot water sytems i.e. no cold water tank so hot water is forced out from the top of the hot water tank by the cold water entering the bottom no cold in no hot out.

         danger here to would turn of any emersion heaters you have untill the cold water comes back on and watch the bar gauge on the central heating boiler. idealy anything that heats the water should be turned off have you seen an unvented boiler explode will take the house with it be carefull!!!!

                  Dave

[Gyn_Paul]

dave,

Although what you say is absolutely true about how vital it is to be sure all parts of a CH are thawed and circulating before turning the heat on again, I don't think the poster has a Central heating system, just a chauffeau.

The Hot flow pipe runs up the inside of the chauffeau and finishes a couple of inches from the top, (for the vertical models) so it will naturally stay full. When you get your cold running again you should find the hot flows too.  Ensure that that is the case and that the thing on the cold inlet (groupe de securite) is thawed and running cold into the drain when you twist the spring-loaded knob a little, BEFORE turning the electricity on again.

On the subject of your warm showers: how hot is the hot by itself? maybe your thermostat needs turning up a bit? Is the system old? could it be furred up?

The other possibility is that the pipework to or from the chauffeau is too narrow in relation to the size of the cold. Do you have a decent mains pressure incoming?

paul

[Dave&Olive]

yes stand corrected but I was just a bit worried that they might have some other source of heating aswell say a wood burner heating the hot water, I would hate anything to happen and thought other people might be in the same position and read the post.    you help him only a diy plumber myself.

                    dave

[Peter72]

From what you describe there seems to be a restriction in the cold water supply to the Chauffe eau, the pressure drop is only apparent when you have a flow

Is the cold tap on the group de securite fully open?,

Is there another valve in the line?

Is there a filter in line with the GdS?

Is there a presure reducing valve in the line to the CE but not in the cold supply?.

Is there a pressure difference between the hot and cold supplies when used alone?

Is the pipework supplying the CE much smaller than that supplying the cold tap?

Sorry it's all questions but they should lead to most faults.

Regards

Peter

[Ianhaycox]

We had a similar problem due to scale build up.

The 60cm internal supply tube in the boiler was solid with calcium. Amazing it worked at all. Lots of prodding with sticks, wire etc. and bingo. Seems that the magnesium anode (which prevents scale build up) has not been replaced in 6 years (since new). After cleaninn I had the BEST shower ever after. The jet was so strong it was almost painful.