Advice on pumps please

[RoyInFrance]

Hello, Further to my post regarding re-using solar hot water panels and pumps etc. at my holiday home in France can anyone provide info on these two pumps please?
Grundfos Multihead G P/N 59506180 PC:1030 Class F
Grundfos UPS 15-50 130 P/N 59525609 PC:9849 Class H
(I have tried unsuccessfully to upload pictures - Any advice on uploading welcomed)

I am trying to re-use as much equipment as possible to avoid it going to the dump.

I believe I will try to create a drainback system using 4 or 5 panels approx 6 - 12 feet above the pump so need to know/understand if either or both of these pump have sufficient power for the required head.

I would also like to know the power requirement of each pump as I may use a PV solar panel with DC/AC inverter to drive the pump if this is possible.
If I cannot power the pump in this way can anyone advise the equipment necessary to turn on the pump when the sunshines?

Also if they will allow drain back through the pump or will I need to be more inventive about where I place the drainback reservoir.

As I will have a spare insulated cylinder I am planning to use this as the reservoir but only partially fill this cylinder. Any reason not to do so?

Thanks

[Bala]

The first pump does not come up on a grundfos site that I can find, only ebay etc.

The second one comes up on a Grundfos site and it has interactive data tables. If you click on the head you need to pump to it will give give you volume and power consumption as well.

That pump is however no longer sold new. There is a tab that will take you to alternatives so you can work out what pump will suit.

https://product-selection.grundfos.com/products/up-ups-series-100/up-ups/ups-15-50-130-96281426?tab=variant-curves

[RoyInFrance]

The first pump does not come up on a grundfos site that I can find, only ebay etc.

The second one comes up on a Grundfos site and it has interactive data tables. If you click on the head you need to pump to it will give give you volume and power consumption as well.

That pump is however no longer sold new. There is a tab that will take you to alternatives so you can work out what pump will suit.

https://product-selection.grundfos.com/products/up-ups-series-100/up-ups/ups-15-50-130-96281426?tab=variant-curves

Thanks,

The first pump has Brisitsh Gas printed on it where the second reads Grundfos,
The first pump has Grundfos printed on it where the second shows Selectric.

The link you gave provides nearly all the info I need except that the head is shown as 50dm - what does the dm mean?
Also I cannot tell from the data if the pump will allow back flow for the drainback.

Perhaps I should design the pipework on the basis that the pump (or any future pump does not allow backflow.
Can some one provide a link to a drainback system design that does not need backflow through the pump?

Thanks again

[LucMan]

"I believe I will try to create a drainback system using 4 or 5 panels approx 6 - 12 feet above the pump so need to know/understand if either or both of these pump have sufficient power for the required head."

You are to vague about your install specs. Pick the the number of panels and the install height. Then the pump can be selected. Rule of thumb 1 gpm per panel. The UPS 15-50 130 is good for 4 gpm at 12' so that should be close to what you need.
A drain back system requires that the water drains back through the impeller on the pump. Always locate the pump slightly below the level off the water in the drainback tank with no traps in the piping to eliminate any air in the pump.
Use a differential controller and line voltage only on a drainback system. The drainback tank needs to be of sufficient size to hold all the water in the the panels and the piping with an air gap at the top, no reason to completely the tank.

[Bala]

I am not sure but the "Head Max 50 dm" may be that the maximum head specs are based on 50mm diameter pipe. But the curve charts are where you get the info you require.

If you go into the documentation section you can download the all the data there is on the pumps with installation guides.

[RoyInFrance]

You are to vague about your install specs. Pick the the number of panels and the install height.

Thanks again LucMan for your advice.
I am vague because I think 1 panel may have damaged pipework on the inlet but if it does not leak surely I want to use all 5 I cannot check the height of the roof until I get back to France in the spring and France have suspended all travel at the moment.

Can you talk some more about the differential controller and Line voltage. I understand the principles but cannot envisage how these would work in a DBS (Drainback system) If the panels and pipework are empty (as they should be) how would the differential controller know to turn on the pump etc.?.
This is why I was considering a small PV panel with a DC/AC converter. This could generate much more than the 50w the pump needs and would automatically operate the system whenever there is sufficient sunshine. If this is an absolutely terrible idea please advise.

Once past the how to turn the pump on I have to consider how the water would drain back once the power to the pump is switched off. I could use a normally open two port valve located after the pump and leading back to the tank. This would close when the pump starts and direct the flow though the panels. When power is stopped it would open and allow the water to drain back into the tank.
This could be a good idea even if the pump allows back flow but do I want the extra complication if not necessary?

Here is a new diagram of the plan
Heating Plan DBS.pdf

Here is the image of the two pumps
pumps.pdf
I had to convert the jpg to a pdf in order to get it to upload. There must be a size limit on images

[LucMan]

DB system.pdf
The beauty of the drain back system is it's simplicity, no valves, no air eliminators- just a pump and a controller.
The differential controller has 2 sensors - one on the panels that senses the temperature of the panel when the sun is shining on it, the other senses the temp of the water storage tank. When the temp of the panel is 7-10 degrees higher that the water temp in the storage it turns the pump on. When the panels are 3 degrees higher than the storage then the controller stops the pump.
The panels will get hot quickly when the sun hits them especially when empty.
The hard part is maintaining a 1/4" per ft slope back to the drain back on the the panels and piping. This is required for all the water in the system to return to the DB tank when the pump turns off.
Search for a gold line GL-30 solar controller

[RoyInFrance]

[ATTACH]n430412[/ATTACH]
The beauty of the drain back system is it's simplicity, no valves, no air eliminators- just a pump and a controller.
The differential controller has 2 sensors - one on the panels that senses the temperature of the panel when the sun is shining on it, the other senses the temp of the water storage tank. When the temp of the panel is 7-10 degrees higher that the water temp in the storage it turns the pump on. When the panels are 3 degrees higher than the storage then the controller stops the pump.
The panels will get hot quickly when the sun hits them especially when empty.
The hard part is maintaining a 1/4" per ft slope back to the drain back on the the panels and piping. This is required for all the water in the system to return to the DB tank when the pump turns off.
Search for a gold line GL-30 solar controller

Thanks for the great advice.
The GL-30 I can only find from USA retailers who only ship in the US, but I will continue to search UK sites. Mostly UK suppliers want to sell and install whole systems but I will persevere.
Why do you think the solar PV panel and inverter method would not work?

Next question, The diagram you provided shows the reservoir on the hot return pipe, surely this would mix the newly heated water with that already in the reservoir thereby reducing the temperature?
Can I also check that the heated hot water enters the top of the coil in the cylinder with cold coming out of the bottom?.

Thanks

[LucMan]

Follow the diagram it is a proven design!