Water heater timer

[Tim_374322116]

Hi, am I the only person who's fed up with having to crawl out of bed to switch the water heater on, then wait 20 minutes before I can get up and shower?

Has anyone come up with a timer to switch the gas side of a Truma water heater on (and off)?

T

 

[Rod_5041370]

I never turn my water heater off when on site as I see no reason to.

What do you think that you are saving?

 

[HomerS1]

Hi, I'm with Rod on this. When I arrive at a site it goes on and when I leave it goes off. Hot water 24/7.

Chris

 

[WatsonJohnG]

I leave mine on all the time except on low amp sites where its switched off for microwaving

It cuts out on the thermostat and at this time of year guards against overnight freezing

 

[Tim_374322116]

I want to turn it off to save gas. I see no point having running over night when I don't need it. Turning it of also save the battery. Also every time it cuts in I hear it as it's under my bed. The current advice from the manufacturer is to turn it off as this is the less wasteful method of operation. In addition, continuous cycling of the heat in my hard water area increases the scale build up.

I have operated it continuously and intermittently and switching it on only when I need it uses much less gas and is therefore better for the environment.

Do you leave you heating on all the time at home or do you run it on a time clock?

Good enough reason??

 

[Tim_374322116]

I never turn my water heater off when on site as I see no reason to.

What do you think that you are saving?

Gas

 

[Tim_374322116]

I leave mine on all the time except on low amp sites where its switched off for microwaving

It cuts out on the thermostat and at this time of year guards against overnight freezing

The electric side is easy as I can use a 240V timer. I want to time control the gas side.

T

 

[trucker]

In fact Tim it is very debatable that you use more energy by leaving the hot water on all the time.

The amount of energy it takes to heat up from cold is at least the same if not more than just topping the heat up now and again on the themostate.

As for leaving my heating on all the time no but your on about hot water not heating. If I had a hot water boiler I would leave that on all the time, but I have a comi boiler so it doent matter to me.

Good enough reply?????????

 

[WatsonJohnG]

Hi Tim

I don't think that there is an answer to the gas via a timer unless Gary has a system

Why not run it on electric at night and switch over in the morning assuming you are on hook up of course

We always use ours on electric but electric and gas when showering.

It could be possible to fit a timer in the 12V ignition side and hopefully someone may come along with the way to do it

Good luck

 

[Tim_374322116]

Hi Tim

I don't think that there is an answer to the gas via a timer unless Gary has a system

Why not run it on electric at night and switch over in the morning assuming you are on hook up of course

We always use ours on electric but electric and gas when showering.

It could be possible to fit a timer in the 12V ignition side and hopefully someone may come along with the way to do it

Good luck

Most of my caravanning is not on mains so gas is my only source of fuel.

 

[Tim_374322116]

The water heater cools down over night between 8pm and 6am, infact in my estimate in the winter the water is cold by about 1am. Therefore simple energy cals say that I'm going to need enough energy to heat the water twice during that period over night. Where as if I switch it off I'm only going to reheat the water once when I turn it on in the morning at 6am.

Also Truma confirm that because of the heat losses from the system the most ecconomic way to run is to heat on demand.

I personally believe this is an area where the manufacturer is dodging the issue and that they should be looking at providing some sort of timer to prevent this waste of energy that occurs when people leave the heaters on all the time.

T

 

[ProfJohnL]

Hello Tim,

Perhaps I can add some facts here.

Firstly, the reason you cannot have a timer on the gas control for the water heater is to do with the legal standard that governs this type of appliance. The control systems is known as a full sequence gas control, and part of the relevant standard effectively says that you a systems whose power is uninterrupted, cannot automatically reset when power is restored. It must require a deliberate manual intervention by the operator to reset and start the appliance.

That is why you cannot simply have a timer circuit that interrupts the 12V power to the appliance.

All control circuits have to undergo a battery of tests to prove the circuit will only fail in a predictable but safe sever manner. This testing does not come cheap or quickly, so whilst it is technically possible to design a control circuit with a timer built in, it is probably perceived by the manufacture not to be worth the cost and effort.

It is definitely more fuel efficient to turn the heater off when it is not required for long periods;

Even though the heater has insulation, there is some heat loss over time. Most manufactures will quite a 'maintenance rate' which is based on how much energy is required to maintain the fully heated water mass in the set temperature band every hour without water usage.

If you want a more definitive explanation please post again in this thread.

 

[Rod_5041370]

My Truma water heater loses 1 degree per hour when turned off and no water drawn.

The water temperature is preset at 70, so it would cool to around 60 overnight.

 

[SteveW77]

I don't think it is as simple as that, as the water cools the rate of cooling will increase, so the drop off will not be a constant rate.

Steve W

 

[Rod_5041370]

The figure quoted is that provided by Truma.

 

[Tim_374322116]

The figure quoted is that provided by Truma.

Truma would not quote me any thermal efficiency figures and I know mine cools right down overnight, not the 10 deg quoted.

 

[Tim_374322116]

Hi John, I've discovered that interupting the power supply does not work however I've examined/traced the control unit circuit and discovered that a (time) switch inserted in series with the switch on the control unit can be used to switch the heater on/off remotely. (i.e. turn the control unit on and then let the timer switch the heater on and off).

It could however also be place in parrallel with the control unit switch which would then operate as an override.

Now all that's needed is a suitable 12V or battery opperated timer. Job done.

T

 

[WatsonJohnG]

Well done !!Result

How about this :

http://www.omniinstruments.co.uk/radiotel/tm848.pdf

 

[ProfJohnL]

Hello Tim,

I am sorry to be the bearer of bad news, but having spent a fair proportion of my working life involved with gas safety I am woefully aware of some of the consequences of owner misadventure with gas appliances.

The current regulations may seem quite strict, but they are there because some people have previously failed to follow guidelines, with undesirable consequences.

In essence, you have to be deemed a competent person to install, service, repair or remove any part of a gas appliance - even in caravans. One of the key requirements is that the manufacturers instructions must be followed. Failure to do so is a breach of the regulations, and that is a matter for the Health & Safety Executive. If the HSE pursue a case, it is treated as a criminal offence, with the attendant sanctions that apply.

With that in mind, any modification you wish to pursue (such as interrupting any part of the control circuit in a way not intended by the manufacturer), must be sanctioned by the manufacturer.

I am guessing that you have not approached the manufacturer with your proposal. I also guess that if you did, you will be told that such a modification is not approved.

Ergo - by making such a modification will contravene the Gas Safety regulations because you are modifying and operating and unapproved appliance.

It has been the law in the UK for some time that all new gas appliances sold must be awarded a CE approval that is only earned after a series of independent tests against a quite strict set of standards.

Because the appliance is not approved you may also be invalidating your insurance though you would have to verify that with your insurer.

Although I am not in a position to assess or judge your suggestion for conformance to the relevant standards, in the absence of any test approval work your suggestion will be technically inadmissible.

 

[ProfJohnL]

I don't think it is as simple as that, as the water cools the rate of cooling will increase, so the drop off will not be a constant rate.

Steve W

Hello Steve W

You are correct about the rate of cooling not being constant, but you have the detail the wrong way round.

Heat loss is relative to temperature difference, so the higher the temperature of the water the greater the heat loss is.

As time goes by the rate of heat loss from a cooling body will diminish.

 

[Tim_374322116]

Bout time the appliance manufacturers got of their fat a***s and gave us what we want. I raised this issue with Carve 10 years ago and they said there was no demand, worse still, they said the most efficient way to run a heater was to leave on permanently. This is complete tripe as they have admitted and I have found out for myself. However it did mean they sold more replacement control boxes.

And to view the gas regs when applied to caravans from a different angle:- is it safer to leave a heater running either while one is out for the day or asleep at night OR have it on a timer and operating only when needed, usually when the van is occupied and the residents awake. Regulations can be a complete a*** sometimes. We will need a CORGI fitter to change our gas cylinders soon.

At the end of the day all I'm doing is inserting another switch that is in addition to the switch on the control unit. Both have to be on for the heater to operate.

T

 

[Rod_5041370]

Tim,

My boiler is an eletric only one, thus it would lend itself to the timer control you seek.

The 1 degree per hour heat loss figure is from here.

The text is a computer translation from German.

Truma Elektroboiler230 V/850 W

Product: 302029

Truma electric boiler

Product descriptions:

The electric water heater has a capacity of 14 liters. The water is based on 230 volts over a heating element heats. Through the innovative isolation of EPP-Geh

 

[ProfJohnL]

Hi Tim,

I am sure that the appliance manufacturers would have designed and supplied timers if their customers (the caravan manufacturers) had requested and were prepared to pay for the cost of such developments, but as with most mass produced products the costs have to be kept low, and a timer is a typical feature that could be seen as an unnecessary luxury.

Truma did produce an E series lorry cab heater with a timer option, but that facility may not be transferable to other products, and may not comply with the latest regulations.

I have to agree with you that sometimes the regulations are stifling new product development costs, but it is a common feature for all manufacturers who sell in the EU.

I can only reinforce my point that any modification to the control system will position the product outside of its scope of approval.

 

[WatsonJohnG]

Tim Have you considered just moving the switch as there is usually plenty of cable

I have done this with the room heater so that I don't have to get out of my seat when I get too hot/cold and years ago I moved the water heater control so that I could switch it on without getting out of bed.

You would then have to find something to do for 20 minutes while the water heated

 

[Tim_374322116]

Hi Tim,

I am sure that the appliance manufacturers would have designed and supplied timers if their customers (the caravan manufacturers) had requested and were prepared to pay for the cost of such developments, but as with most mass produced products the costs have to be kept low, and a timer is a typical feature that could be seen as an unnecessary luxury.

Truma did produce an E series lorry cab heater with a timer option, but that facility may not be transferable to other products, and may not comply with the latest regulations.

I have to agree with you that sometimes the regulations are stifling new product development costs, but it is a common feature for all manufacturers who sell in the EU.

I can only reinforce my point that any modification to the control system will position the product outside of its scope of approval.

Have located a very neat battery operated timer with a built in relay for under