Confused about pump positioning in a geothermal water system

[conorr51]

Hi all, I have spent the last few weeks reading through various posts on this website about installing a pump in our house. The current set up is a gravity fed system, with both solar and geothermal heating of the water. It is a new build but from the time we moved in the pressure in the system has been terrible. So I've finally bitten the bullet and decided to install a pumped system. I've bought two single impeller pumps (Stuart Turner 46419 Monsoon 3.0 bar) but am looking for some advice on where to best place the pumps. I've attached a rough diagram of the system in the house. Now I know that best placement would be beside the hot water cylinder, but as we have a geothermal heat pump also heating the water, we have a second hot water cylinder on the ground floor, which seems to be fed from the 1st floor hot water cylinder. So if you look at the diagram would I be right in saying that the 1st pump should connect to the cold feed from the storage tank which is going straight to the cold outlets (I've marked the pump with an X), but should the second pump be attached at point A, B or C....or none of them I might be completely wrong with all of this so am hoping someone far more qua than I am can have a look! Thanks for all the help, Conor

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• conorr51
• 7 Feb 2014
• 1

 

[conorr51]

Hi again, just wondering if anyone had any help/advice with regards to my problem. The pumps have arrived and I was hoping to try and install them tomorrow. Any advice at all would be helpful. Thanks again, Conor

 

[mogget]

In my (DIYer) opinion I would put the pump at point B or C. But am happy to be corrected.

 

[mogget]

Bit odd that your heat pump cylinder doesn't have a vent though - although I know not Irish ways of doing things.

 

[conorr51]

thanks for the help mogget! Would it having a vent make a difference? Can go and have a look at it now if that would help. What would I be looking out for?

 

[mogget]

Can go and have a look at it now if that would help. What would I be looking out for?

You'd be looking for a pipe coming out of the top of the cylinder going to the cold water tank up top.

I know next to nothing about ground source heat pumps, but more about hot water systems and shower pumps. It's possible that if there was absolutely no way the heat pump cylinder could boil, it might not need a vent. Or there could be some sort of temperature / pressure relief valve.

 

[conorr51]

no there doesn't seem to be. Two pipes seem to be connected to it, one bringing water down from the upstairs cylinder, the other bringing the water back upstairs for distribution to the house if you understand what I mean? Confusing stuff for a diyer to figure out

 

[mogget]

Oh well, that's the way it is I guess - unless someone else chips in we'll probably never solve the mystery. But anyhow, position B or C for the pump with B being preferable as air would be more likely to collect at C and airlock the pump.

 

[conorr51]

Haha Thanks for the advice mogget, it is most appreciated! Hope you enjoy the rest of this fine evening!!

 

[mogget]

You too, it's fine here too

 

[hanns21]

When you bought the pump was there not instructions on where to fit?? Certain manufactures request you to fit in a certain position to cover warranty and to stop air etc it should never pump into a cylinder so that rules out (a) it should be position on the outlet of cylinder at the base of it. Also a blending valve set at roughly 55 degrees otherwise it will burn out pump. Hopes this helps.... All i can remember of my head

 

[conorr51]

Thanks hanns21 for the advice! The pump comes with great instructions, and I can even find videos on the Stuart Turner website that show how to install, the only problem is that I cant find anything which seems to resemble the geothermal set up in this house! The fact that there is two hot water cylinders, one upstairs and one downstairs, has made this a very confusing proposition for me And as you point out, the last thing I want is a burnt out pump as they definitely weren't cheap!!!

 

[mogget]

Don't shower pumps (which are basically what these are) usually take their hot supply directly from the cylinder without blending valves? The cylinder water may be significantly higher than 55 degrees. Conorr, do you have the pump instructions? They should tell you the maximum permissible water temperature.

 

[mogget]

Done it for you, 65 degrees is the maximum, and you don't want your cylinder any hotter than that.

 

[conorr51]

Thanks for the research mogget, so what you are saying is to make sure the temperature of the water in the cylinders should never exceed 65 degrees?