Air source heat pump/immersion heater query

[sparkysy]

Yep that will do it, contactor and timer for boosting the water to kill off the legionaires.
You may be able to alter the timer to come on for longer or more times in a day to get a longer time heating the tank, but from this I would say that the immersion is independent from the ASHP which is what I first thought.

 

[Welderpaul]

Yep that will do it, contactor and timer for boosting the water to kill off the legionaires.
You may be able to alter the timer to come on for longer or more times in a day to get a longer time heating the tank, but from this I would say that the immersion is independent from the ASHP which is what I first thought.

That's good news. I'll print out the instructions for it and see what i can do. It will be a pain to have to keep fiddling with that tiny timer though every time its cold and i need to boost it. Is there an easier way to have this set up?

DHW is already warmer tonight with a cobbled-together temporary feed to the upper immersion. I'll sort it with a permanent feed over xmas, and i'll control it with a timer like this so at least i have some basic control over immersion on/off times over cold spells, and can just over ride it off when temps get over 0 degrees and the ASHP starts working properly.

 

[sparkysy]

You could retrofit the same type of timer to that contactor in place of the din mounted one and it would do the same job and be easier to switch on and off! Glad that the addition of the top one has made an improvement in temperature!
Bottom one will always be better as its heating the tank from low down so will cycle more heat past the coil than the top one would.
Sy

 

[Welderpaul]

You could retrofit the same type of timer to that contactor in place of the din mounted one

Thanks Sy

How would i do that?

I'd need the bottom immersion to come on to do it's legionnaires cycle even when the time clock has been over ridden off.

 

[sparkysy]

No problem,
You could parallel the two timers running the bottom immersion so that the din mounted one still continues to do its thing while the new one is under your control.

 

[addjunkie]

Thanks Sy

How would i do that?

I'd need the bottom immersion to come on to do it's legionnaires cycle even when the time clock has been over ridden off.

Youd need so e kind of dual control, one for legionaires all year round, and one run off a timer or thermostat for when its really cold outside, when ASHP isnt up-to much, a regulated input would be better just topping up, rather than; full tilt

 

[Welderpaul]

No problem,
You could parallel the two timers running the bottom immersion so that the din mounted one still continues to do its thing while the new one is under your control.

It would be ideal to leave the din mounted timer/contactor doing its thing and to supply the bottom immersion with another feed (Presume then another 2.5mm feed off a seperate MCB with a timer same as the upper immersion?) but this would then back feed the other supply?

 

[Welderpaul]

Youd need so e kind of dual control, one for legionaires all year round, and one run off a timer or thermostat for when its really cold outside, when ASHP isnt up-to much, a regulated input would be better just topping up, rather than; full tilt

That's exactly how I want to do it!

 

[Gareth J]

That's exactly how I want to do it!

My simpleton brain suggests a central heating programmer could be used. Although it wouldn't be rated for 13 or whatever, amps. So would need a couple relays to use one. But maybe there are heavy duty dual output controllers.

Not had a lot of luck with those ^ digital time clocks from timeguard or greenbrook. I've had several die. A boring analogue time clock will probably last better.

 

[Welderpaul]

A single timer rated at 16A which would be a simple flick over between 'warm' and 'cold' weather settings would be ideal. One set of timings for legionaires prevention and the other set of timings to do the 'topping up'.

 

[addjunkie]

Do you have solar panels on the roof too! If you do, I would suggest putting in a 3rd control.
One of these, there are others. Unless you have the battery wall too.

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If you down load the manual, as well as floating power to imersion heaters (2) independantly, they also have a boost function. So in effect. Push the button when cold and itll switch one or both immersions on. So could boost your heating, but when the sun is out any export to the grid from PV goes into your heating or hot water.

problem with using an imersion as heating with a coarse full power on or off, itll be expensive to run.

 

[Welderpaul]

No solar panels.

problem with using an imersion as heating with a coarse full power on or off, itll be expensive to run.

Indeed, but the next best solution to ripping everything out and installing an oil-fired system.
A decent timer system should help to economise use of immersions best i can.

 

[Kayos]

No solar panels.


Indeed, but the next best solution to ripping everything out and installing an oil-fired system.
A decent timer system should help to economise use of immersions best i can.

We can increase efficiency in systems upto 25% using smart controls. Obviously fairly complex and for big systems, but the same principles apply

 

[sparkysy]

There is no need to over complicate the bottom element, leave the existing timer connected and use the same supply and contactor to feed your new timer and the contactor to switch it. Then just run a new supply and timer to the top immersion. Less to go wrong and easily adjustable.
Sy

 

[Welderpaul]

There is no need to over complicate the bottom element, leave the existing timer connected and use the same supply and contactor to feed your new timer and the contactor to switch it. Then just run a new supply and timer to the top immersion. Less to go wrong and easily adjustable.
Sy

I am simple, i still can't understand how i get the two timers to work together without interfering with each other..

 

[sparkysy]

Yes top correct dp switch to timer then immersion heater.
Bottom one use the supply from the existing timer live and neutral. Then run your switched live out to the contactor coil same as the din mounted timer. This way either timer can control the heater without conflict.
If that makes sense!
They can't really interfere with each other as if the din one is on and the other one switches it will just override the din until the time ends
Sy

 

[Welderpaul]

Like this?

Would still back feed though?

I'll bypass the timer tonight to see how much difference it makes to temperatures.

 

[sparkysy]

Yep that's it just run the 2 timers in parallel.
sy

 

[Gareth J]

That's good news. I'll print out the instructions for it and see what i can do. It will be a pain to have to keep fiddling with that tiny timer though every time its cold and i need to boost it. Is there an easier way to have this set up?

DHW is already warmer tonight with a cobbled-together temporary feed to the upper immersion. I'll sort it with a permanent feed over xmas, and i'll control it with a timer like this so at least i have some basic control over immersion on/off times over cold spells, and can just over ride it off when temps get over 0 degrees and the ASHP starts working properly.

If the system can cope with just boosting the DHW and not the lower immersion (which would include heating for the house presumably), maybe worth seeing if it'll cope with that first?

Theory being that, DHW is helpful at higher temperatures, which the HP may be struggling to achieve. While should still be giving a reasonable cop getting water for space heating to, what, 40C?

If it copes with just boosting the top immersion, could be a wiring win and an efficiency win.

 

[Welderpaul]

If the system can cope with just boosting the DHW and not the lower immersion (which would include heating for the house presumably), maybe worth seeing if it'll cope with that first?

Theory being that, DHW is helpful at higher temperatures, which the HP may be struggling to achieve. While should still be giving a reasonable cop getting water for space heating to, what, 40C?

If it copes with just boosting the top immersion, could be a wiring win and an efficiency win.

That's how i have it rigged at the moment. The top immersion very quickly gave us hot DHW back as normal, but no effect on the heating which is still dropped too low and the thermostats are constantly calling for heat.
Hopefully rigging the bottom one will give us heating back to normal, and ease the load on the ASHP.

Timers on the immersions and only having to use them at circa 0 degrees outdoor temps will keep it as 'efficient' as possible given the circumstances.