by ericmark »
Wed Jan 13, 2010 2:08 pm
The problem is where two or more direct heating showers are used at the same time on top of the normal usage it can exceed to incoming supply.
Alternative is to store the heat, or use another form of heating. i.e. direct from combi-boiler.
The tanks are the main expense there are four main types.
1) Open vented both for circulating water and cleansing water.
2) Open vented for circulating only.
3) Open vented both for cleansing water only.
4) Closed for both.
With open vented systems you often have to pump. The power shower. With closed systems the supply water pressure is enough. There are two systems using closed system for the cleansing water one where the tank is pressurise and a hot coil passes through the water and a second where the tank is open vented and the very efficient hot coil with cleansing water going through it is heated.
The main thing is lime. Where I live we have very little lime in the water kettles last years and years and we can fit what we like. But Lime is deposited more as the water temperature rises so the Glen hill idea with a supper efficient hot coil would have advantage both as 12 month inspections are not required and lime build up is reduced.
But although it does have a very good heat exchanger one shower is about the limit.
The Mega Flow has more of a problem with lime and needs testing once a year because the whole vessel is pressurised however you can have multi showers.
The AGA presents a different problem in that it can boil the water. Every other system has some form of auto shut down. The Glen Hill is better here as you can get rid of any steam without damage however the header tank has to be a special able to hold boiling water. The electrics also change as most immersion heaters have a safety device non reset-able which since it can be ruptured by the AGA is no good and one which can be reset is required.
It may also need the ability to be cooled either by dumping hot water and replacing with cold or by pumping water around some form of heat exchanger to safely dump unwanted heat. Like the Kenlow fans used with car radiators and this means a reliable means to circulate water and/or drive fans.
12vdc or 230vac derived from batteries to drive these pumps and fans are a must. I worked out for my sons boat about 2 gallons minimum is required in the header tank to ensure should it start to boil the water will not boil dry before the fuel in the stove is used up.
With these considerations not really a DIY job. Son is an electrician and his wife is a Plumber and even so they got the wrong type of header tank and this now needs to be changed.
However once a water storage system is installed one can add on to it. So solar panels and wind generators can add to the system.
You give so little information I can only give general answer but it should get you started.
