We are in the process of redoing our house (big extension on the back a
well as the attic being converted) it's now down to me to do all th heating, plumming , electrical etc. The advice i need is i have a system boiler but i can't decide on th size of the hot water cylinder i need. We're probably going to get range tribune indirect cylinder but reading their litrature i'm gettin confused , one page says a 150L will be ok (the house has 3 bedrooms , bathrooms for the moment) the next page says either a 180L or 210L . I'm going along the lines that i want a bit of redundancy built in s as we never run out of hot water but i don't want to go over the top. Any advice / comments greatly appreciate
Ive got 250L and its easy to run it cold with a couple of big baths, or one bath and a bit of hand washing.
Only you however, know whether spending an hout an a half in water up to your chin reading Lord of The Rings is a regular feature, or if your wife regularly leaves hot taps running all afternoon..Or indeed if you have hygienically challenged kids who are obsessive compulsive about a shower every five minutes, all at the same time.
I have a 210 litre cylinder for exactly that reason.
There are really four considerations.
1) What is the footprint on the floor? I found that they are the same above a certain capacity and the height changes
2) What is the height? Usually this is not an issue, though.
3) Heat loss. As long as the cylinder is adequately insulated with (e.g.) 50mm of foam, there is very little heatloss and one can reasonably go for large capacity.
4) Heating the cylinder.
The aspect of this is that one wants to reheat the cylinder quickly. To that end, a fast recovery type should be found and used together with a fairly powerful boiler. Most system boilers modulate, so even if the CH requires only 15kW, you could go for a 30kW boiler. That will heat the cylinder quickly but drop down in power for the CH.
The Tribune meets those requirements.
I'd go for the 210litre, but the 150 and 180 may well be OK - it would depend on the pattern of use. You could do the sums based on an assumed pattern of use, cold water temperatures and so on. I decided that that was not a meaningful exercise because there were too many variables. As a result, I used a 210 litre and forgot about it.
Unvented cylinder? Forget it. It is no more expensive and probably cheaper to have a high flow Rinnai multi-point. It will give hot water for ever. Hav ethe CH boiler do CH only and the multi-point do DHW - they have models which can be fitted outside to save space. From a recent post of mine:
I know he detested the tank in the loft as it got in the way. He also didn't like the cylinder taking up space too. His house is a three floor town house with garage on the ground floor, heated by forced air which they love. One bathroom two showers. I suggested they spend some extra and go for a high water flow Rinnai multi-point in the loft on the gable end. Rinnai and Andrews have models which can be fitted "outside" too, saving lots of space in the house. They said yes, seeing the benefits of space saved and long showers. They get annoyed when the cylinder runs out of hot water when showering which happened far too often for them, and in the mornings too as the immersion does not recover fast enough when consecutive showers are taken.
I fitted the Rinnai last week with a flow switch in the cold supply, and the room stat of the forced air heater run through the switch, so when DHW is called by the Rinnai the air unit is switched out as the gas meter is not big enough. The air unit is a conventional flue job, with a simple gas multifunction control. The whole job took less than a day to do.
What happy bunnies. They rave over the mains pressure showers and the space they have gained. Two showers can be had whereas before they could not have two together only one with big gaps between. Now they have showers for as long as they want and when they want. The bath fills up as fast as before too.
They like the idea that the DHW temperature can be controlled by a waterproof remote temperature controller. They never went for it, but is can be easily fitted after. So you can lay in the bath and control the temperature of running hot tap. The Rinnai can have up to four of these.
Rinnai and Andrews high flow multi-points are very cost effective. And now are cheaper than fitting unvented cylinders.
On Sat, 25 Nov 2006 15:50:44 +0000 someone who may be scubabob wrote this:-
Where are you intending to place this cylinder? Where is the boiler?
Has the extension and existing house been arranged so that draw-off lengths are minimised? If it hasn't been then it may be that more than one source of hot water is more suitable.
That sounds a bit strange. A fast recovery system should have the tank back up to temperature soon after a normal length bath. Unless the bath is a Roman one. ;-)
Not many are going to entertain the idea of a second boiler purely for water. Extra installation and capital costs, extra space wasted, and extra maintenance. Most house buyers (which seems to be important to dribble) would run a hundred miles when confronted with such a set up.
Right. If running out of hot water is a problem because of the boiler programming, might be worth fitting more comprehensive temperature sensing on the cylinder and leaving the boiler enabled?
Ah. I can perhaps understand leaving the cold water running when washing vegetables etc, but the hot?
The best way would be to fit twin stats to the tank - so the boiler can't just top up the tank, but waits until it's near empty. If that's what you prefer. Although with a well lagged system and reasonable runs from storage tank to boiler I'm not sure it makes a great deal of difference.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.