seocndary DHW circuit components help needed

[acideraser]

installer told me I need following for a secondary HW circuit:
Non-return valve
controller
contact thermostat
circulation pump

It is ecotec 624 with unistor cylinder, both vaillant
my understanding is i need brass or stainless steel circulation pump, grundfos or wilo would be the best, but what about controller and thermostat?

would it be VR40 controller or something else ? if so does it come olready inside the boiler or should be bought separately?
and what about thermostat ?

System will be wired to VR61/4 and 2 CH controlled by VRC470 and VR81 respectively

thanks

 

[Dan Robinson]

Grundfos do one with everything built in. Just plumb it in with service valves and plug it in the mains.

 

[acideraser]

Thanks Dan do you happen to know the exact model as i couldn't find specific details on their website. Is it UPS 15-50N like this one

http://www.anchorpumps.com/grundfos...Yv6ZC4-9rf74H1HnOshU6NLSCem_qTLIqEaAh0H8P8HAQ

still not clear what VR40 is and how to find it?

 

[Dean744PiN5]

thats just a plain old hot water circulator.

this is the one

http://www.anchorpumps.com/pump-typ...mfort-hot-water-circulator-pump-240v-96433884

 

[strowger]

installer told me I need following for a secondary HW circuit:
Non-return valve
controller
contact thermostat
circulation pump

It is ecotec 624 with unistor cylinder, both vaillant
my understanding is i need brass or stainless steel circulation pump, grundfos or wilo would be the best, but what about controller and thermostat?

would it be VR40 controller or something else ? if so does it come olready inside the boiler or should be bought separately?
and what about thermostat ?

System will be wired to VR61/4 and 2 CH controlled by VRC470 and VR81 respectively

thanks

I have this type , although my Ecotec is a 618 not a 624, installed this spring. Ecotec 618, Unistor, 2 CH zones controlled by VR 61, VRC 470, VR 81 upstairs as thermostat for the second zone, VR 40, grundfos brass pump. Also a USB eBus coupler and data logging on a PC, but that's another story...

Grundfos brass pump - not the one with built-in timer etc - driven by VR 40 and timer controlled by the VRC 470.

The VR40 has to be bought separately and fits inside the boiler next to the PCB. It's not Vaillant's finest ever effort at design but it works. If you buy the VR 40, the pump attaches to it, you set a couple of registers on the boiler (instructions come with the VR 40), reboot the boiler, and then the VRC 470 will gain options to configure times for the pump to run.

Alternatively you can control the pump without using the Vaillant controls, and not bother with the VR 40 etc. There are some attractions to this route (eg you can do stuff like put PIRs in the bathrooms to bring the pump on) and it's probably cheaper.

On a slight tangent - check the thermostat on the immersion in your Unistor if you haven't tried it yet. It's the only British-made piece of the whole kit and mine barely manages 45C on the highest setting - total rubbish.

 

[acideraser]

Thanks, very clear!

connection to PC and alternative controls and PIRs in bathrooms sound very interesting though.

 

[strowger]

Thanks, very clear!

connection to PC and alternative controls and PIRs in bathrooms sound very interesting though.

The thing I've found with the secondary circulation is that even with lagging on everything it still wastes a lot of heat - the unistor cools much faster with it running. Hence the talk of PIRs.

If you live somewhere where the heating is on 9 months of the year anyway, and your pipe runs are mostly in heated/inhabited spaces, you might not care since the "lost" heat is in to the living space you were heating anyway.

Now it's in and running, the secondary DHW circulation is frustrating me a bit here - because

a) I don't think it needs to be a constant pump really even during the times it's set to come on - I'm sure 1 minute on/4 off would give adequately-warm water at all the showers instantly. The Vaillant controls aren't going to let me try anything like this.

b) There's a trade-off between cylinder temperature and capacity - a 200litre cylinder at 65C can give a lot more showering than it can at 50C - but the higher temperatures mean much higher loss from the secondary circuit.

All that said, definitely do install it if your place is big or has long pipe runs - it's fornicating lovely to have the shower run instantly hot, especially when you have a screaming and faeces-smeared toddler to hose down.

 

[Norcon]

Multifunction timer does the job set to about 30 seconds on in every 40 minutes.
Pipes should be lagged with armaflex class O 25mm wall minimum.

 

[acideraser]

Multifunction timer does the job set to about 30 seconds on in every 40 minutes.
Pipes should be lagged with armaflex class O 25mm wall minimum.

Thanks for the tip, should timer be connected directly to pump and will it override main programmer settings or just add timed running time within time periods defined by Vaiilant timer-programmer?

 

[acideraser]

Hi Strowder,

Thanks for all information , I also found your other posts and read all that stuff in Russian about boiler commands connection to PC etc - very interesting.

Have a question about your current setup - do you have a temp. sensor in your HW circulation circuit or it's just VR40 and pump?

My plumber keeps saying there also must be a thermo probe or thermostat though I don't understand what for....

cheers

 

[strowger]

Multifunction timer does the job set to about 30 seconds on in every 40 minutes.
Pipes should be lagged with armaflex class O 25mm wall minimum.

Thanks for the tip, should timer be connected directly to pump and will it override main programmer settings or just add timed running time within time periods defined by Vaiilant timer-programmer?

Thanks for all information , I also found your other posts and read all that stuff in Russian about boiler commands connection to PC etc - very interesting.

Have a question about your current setup - do you have a temp. sensor in your HW circulation circuit or it's just VR40 and pump?

My plumber keeps saying there also must be a thermo probe or thermostat though I don't understand what for....

The Vaillant timer-programmer (actually the VR 40 unit in the boiler) just feeds the brass pump with 240V mains during the scheduled times.

I wonder if there's such a thing as a timer which could go between the VR40 and the pump, and give say 1 minute on every 4 minutes - I assume previous poster Norcon meant 4 rather than 40. If it significantly shortens the life of a £200 pump, it may not be worth doing....

My previous posts, and website, relate to a much older and inferior way of interfacing a PC to eBus devices. At the time I wrote them, the eBus coupler and ebusd open-source software didn't exist. All best ignored now I'm afraid - in fact Vaillant don't release vrDialog any more and the old versions won't talk to modern kit.

I didn't think there was any kind of thermostat or temperature sensor on the HW circuit. I've actually just spoken to my plumber (he's here, building a bathroom) and he confirms it. The only sensors are the two which the Unistor has anyway - the one which the controls use to sense when it needs to be heated, and the old-fashioned cylinder stat which acts as a safety back-up.

 

[acideraser]

Thanks Stroger, this is what I thought as well.
Will explain to him that all controlled by VR40.


Now that you mentioned that timer may shorten pump life, I could probably just let it run at the lowest speed during the times when DHW is required and add armaflex lagging anyway.

Since I am changing from a 15 year old Ideal boiler and vented sysment I am hoping the new heating/DHW arrangement will be more efficient anyway

 

[Dan Robinson]

To switch it off when the pipe work reaches temperature.


Look at the Grundfos UB 20-14BXUT . Product number 96433890

 

[strowger]

Thanks Stroger, this is what I thought as well.
Will explain to him that all controlled by VR40.


Now that you mentioned that timer may shorten pump life, I could probably just let it run at the lowest speed during the times when DHW is required and add armaflex lagging anyway.

Since I am changing from a 15 year old Ideal boiler and vented sysment I am hoping the new heating/DHW arrangement will be more efficient anyway

You DEFINITELY need GOOD lagging everywhere. And to be really fussy about stuff like joins, pipe clips, corners - everywhere heat escapes.

Yes, definitely pump at slowest speed.

 

[acideraser]

To switch it off when the pipe work reaches temperature.
Look at the Grundfos UB 20-14BXUT . Product number 96433890

Thanks Dan, now it makes sense why thermostat may be required.
That pump looks cool and seem to have both timer and thermostat but 330 quid for a pump is too much for me. I already acquired Grundfos UPS 15-50N for £90...

Do you know if there is a simple thermostat which could be connected to a pump and stop it once hot water is pumped through the pipe during time periods set on Vaillant programmer ?