moorey56 Posted April 23, 2016 Share Posted April 23, 2016 Hi When out in my van when we use our boiler to proivide heating/water my wife and i always have a debate as to whether it uses more gas to keep the hoit water on permanently or turn it off when we know we won't need it. This annoys her as we have to wait a bit in the morning for hot water !!!! Can anyone advise what the most efficient way is for the hot water in particular? Many thanks Simon Link to comment Share on other sites More sharing options...
Geeco Posted April 23, 2016 Share Posted April 23, 2016 Hi Simon, I do not have an answer to your question however a solution is to introduce a timer into the system. This will allow you to turn the boiler on in time to use it with out the waste. In our case the boiler is under our bed, fine in winter but not so good in summer. The standard fitment timer solved the problem. It will probably be the compromise you need. Remember in any relationship you can be right or happy. I chose happy! Cheers, Link to comment Share on other sites More sharing options...
StuartO Posted April 24, 2016 Share Posted April 24, 2016 Leaving your gas boiler switched on all the time is bound to use more gas than if you only heat water when you need it. This is because the water storage is not well insulated (compared with a domestic hot water cylinder for example) so keeping the water hot will inevitably involve loss of heat, therefore consumption of more gas. There is a sensible balance to be struck of course, so you probably won't want to be too anal about turning the boiler off and on all the time if you need hot water fairly frequently. How much extra gas will be used leaving the hot water on all the time in a motorhome is an interesting question and although I have never actually measured it, I suspect it will be a significant amount. It's not just the cost of the gas which is significant but you might also find yourself having to change bottles and hump those about more often. It's a different story if your hot water boiler can run on mains electricity and you are on an unmetered EHU, when you might as well have the convenience of leaving the hot water on all day. My OH is convinced our boiler smells "hot" if it's on continuously, so I'm not allowed to leave it on overnight for that reason anyway! Link to comment Share on other sites More sharing options...
mgnbuk Posted April 24, 2016 Share Posted April 24, 2016 We turn our Combi 4 (gas only model) on when we arrive on site & don't turn it off until we break camp. It comes on maybe once or twice a night to "top-up", but doesn't run very long when it comes on. Our gas consumption total (including occasional use of heating early mornings at higher altitudes and cooking as required) is less than a litre a day during summer use - having a Gaslow cylinder allows easy monitoring of gas used. We usually use the shower daily for the two of us, plus washing & washing up, with the heater set to maximum water temperature, so probably heat around 10-15 litres a day (our normal water consumption is 20-25 litres a day). Our previous van had an seperate, gas only, Truma water heater (Ultrastore ?) which we used in a similar way. IIRC that heater had a rated gas consumption of 70 grammes/hour. We didn't have Gaslow on that van, but a single 13Kg propane cylinder lasted for 17 day continental trips with 3 or 4 kg left. That heater was possibly not as well insulated as the Combi, as my recollection is that it cycled a bit more frequently overnight. But that van (CI Carioca 22) was also not as well insulated as our current Roller Team T-Line, so there was maybe more heat loss from the area surround the water heater. than there is now. I prefer the convenience of hot water when required (on tap ?) to any (minimal ?) gas savings. Given the infrequent, short, "top-ups" compared to the time taken to heat up a tank from cold, my feeling is that it uses less gas to keep a tank full hot all the time - doubtless other opinions will be along shortly. HTH Nigel B Link to comment Share on other sites More sharing options...
colin Posted April 24, 2016 Share Posted April 24, 2016 The FACTS are that it takes more energy to maintain the heat overnight,it's a simple matter of physics and has been proved to be the case on even better insulated set ups. The difference in cost I cannot tell you, and then there's the convenience of having almost instant hot on tap if that is what you want. It is a well known problem with some Combi set ups that hot water only heating will produce an acrid 'plastic' smell, whilst this is not supposedly dangerous it can be unpleasant, to counter this on our set up we close the two highest heat vents. Link to comment Share on other sites More sharing options...
Colin Leake Posted April 24, 2016 Share Posted April 24, 2016 StuartO - 2016-04-24 11:18 AMLeaving your gas boiler switched on all the time is bound to use more gas than if you only heat water when you need it. This is because the water storage is not well insulated (compared with a domestic hot water cylinder for example) so keeping the water hot will inevitably involve loss of heat, therefore consumption of more gas. There is a sensible balance to be struck of course, so you probably won't want to be too anal about turning the boiler off and on all the time if you need hot water fairly frequently. How much extra gas will be used leaving the hot water on all the time in a motorhome is an interesting question and although I have never actually measured it, I suspect it will be a significant amount. It's not just the cost of the gas which is significant but you might also find yourself having to change bottles and hump those about more often. It's a different story if your hot water boiler can run on mains electricity and you are on an unmetered EHU, when you might as well have the convenience of leaving the hot water on all day. My OH is convinced our boiler smells "hot" if it's on continuously, so I'm not allowed to leave it on overnight for that reason anyway!Same here she also claims it smells hot if I run it on the higher electrical setting. Academic because she's got a two KW kettle so if I left heating or water on high setting we would trip,the bollard. Just a tip with a combi system if you are using it on electric only you'll never get the water realy hot if you have the heating on at the same time. Indeed if you start with the water hot then turn the heating on it will take some of the heat from the hot water and reduce its temperature. Link to comment Share on other sites More sharing options...
breakaleg Posted April 25, 2016 Share Posted April 25, 2016 Just a thought, wouldn't it burn the heating element out more quickly thus the cost of replacing it.? Pete Link to comment Share on other sites More sharing options...
Guest pelmetman Posted April 25, 2016 Share Posted April 25, 2016 Its always puzzled me why the industry changed from the instantaneous gas geyser type to the Truma boiler type? :-S ........... As now folk are limited to what hot water is in the small boiler, where as with the old system your hot water supply is limited to whats in your on board tank ;-) .... Admittedly they do have a electric option when on EHU, but from what I hear its rarely gets the water hot enough :-| ....... Link to comment Share on other sites More sharing options...
rogher Posted April 25, 2016 Share Posted April 25, 2016 I imagine that the old type of instant heater became outlawed because there was no flue to the outside. Modern heaters have combustion units that are sealed from the living quarters. Although you will use more heat (so more gas/electricity) by leaving the heater on, I consider the cost to be worth it in terms of convenience. The extra heat used will be more significant in winter but not in vain as most will be ‘lost’ to the living area. Link to comment Share on other sites More sharing options...
lennyhb Posted April 25, 2016 Share Posted April 25, 2016 I fitted a CP-Plus controller to my Combi 6, I set timer so when we get up in the morning hot water for a shower is available. Link to comment Share on other sites More sharing options...
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