Salamander RP50 PH 1.5 bar Pump Problem

[Philayl]

Hi, I am wondering if anyone can help with the following problem, I'm sorry it's a bit lengthy but I wanted to put as much information as possible in. For the last 8 years I have powered my shower with Salamander RSP50 1.5 bar pumps, the second pump in that time went faulty a couple of weeks ago, so no problem I purchased a new Salamander RP50 PH pump, which is the direct replacement for the now discontinued RSP50. Fitting it was a no brainer just turn off the valves on the stainless flexi couplings, undo the unions on the pump and remove the 13 amp plug from its socket, reverse procedure and all done. Ever since installing it I have had water coming out of the hot water cylinder header tank overflow, at first I suspected the ball cock so replaced it with a new one, still overflowing, so suspecting a duff new valve I bought a good quality Pegler ball valve and fitted it. The water was still coming out of the overflow, so I had to give this a lot of thought, it only started overflowing when the hot water hadn't been run off for an hour or more, and each time I went in the loft to investigate I found the separate cold water header tank for the shower filling. I eventually put two and two together and realised the new pump had what is called "Crossover" technology, this meant should either the hot or cold supply cease the impeller on the other end of the pump would be fed through a tube linking both impellers to stop one of them burning out. But what is happening is that the cold water header tank for the shower is in the loft 8 feet above the pump and the hot supply is from the cylinder next to the pump in the airing cupboard, because of this crossover tube the water from the cold header tank is pushing the water back up the hot water cylinder overflow pipe, which is lower than the bottom of the cold water tank feed to the pump, into the hot water header tank, I confirmed this by closing either of the valves on the stainless flexi pipe feeding the hot or cold water inlet to the pump. Sorry for going on so long but what I would like advice on is can I just put a non return valve in the pipe coming from the hot water cylinder outlet to stop the water being pushed up the header tank feed, or are there other better alternatives. All piping and fittings from and to the pump is 15mm polypipe and JG push fittings, but nearly all non return valves I have seen say not to be used with central heating, and would the hole in a 15mm non return valve restrict the hot water flow to the pump? Phil

 

[terryplumb]

I found your post a little confusing ,can you please clarify a few things... The cold water tank in the loft does this supply the hot water cylinder and the shower pump ,or are they fed from two separate tanks ,as your post implied ( which would be very unusual ). How is the water in your cylinder heated ,from central heating boiler ?when you say water is coming out of the hot water cylinder overflow ,what exactly are you referring to ?

 

[Philayl]

Hi, the hot water cylinder header tank and the shower pump cold water header tank are both situated in the loft and are separate, the hot water cylinder is a vented indirect one heated by the boiler, the water is coming out of the hot water cylinder header tank overflow, but while this is overflowing the cold water header tank going to the pump is filling, so the cold water is going in a loop down to the pump straight through the pump "crossover" tube and out of the hot feed side of the pump up to the hot water cylinder header tank when the pump is not running. I hope this makes things a bit clearer. Phil

 

[terryplumb]

Do you know why the cold feed to the shower pump was not taken from the loft tank that supplies the hot water cylinder , that would have given a balanced hot and cold supply to the pump. I understand what you are saying ,but can't help but think that you are wrong .as I understand the " crossover " only functions if one or other supply to the pump fails ,but your pump has both hot and cold supplied to it ? So in theory the two supplies can't mix within the pump ?

Edit.. Are you sure your new pump is RP50PH ,or is it RP50PT ?

 

[Philayl]

Hi terryplumb, this is the way the plumber installed the shower, I am not aware of the rights or wrongs of the installation. The water is not actually mixing inside the pump the cold is being forced through the pump, I assume by gravity, and up into the hot water header tank, I apologise you are correct the model is the RP50PT. I am not very good with diagrams but have uploaded a very rough one of the system (nothing to scale!), there are shut off valves on the feed pipes entering the pump, if I close the one on the hot water feed the overflow from the hot water header tank stops running. Phil

 

[terryplumb]

If you close the valve on the cold feed to the pump ,and leave the other valves open ,what is the result ? Your pic shows that water is entering the cold water storage tank ( that feeds cylinder) via the vent pipe ,which goes much higher than the top of the storage tank ,then bends downward into the tank. Is that actually so ,or just an anomaly in the way you sketched the layout. Is the cold tank that supplies the shower at a much higher level than the one feeding the hot water cylinder ? And finally do you have a third tank ,known as a feed and expansion tank ,which supplies water to your boiler and radiators ,or is your central heating a sealed and pressurised system.

 

[Philayl]

Hi, the overflow stops whether it is the hot or cold supply valve that is closed, as stated the sketch is not accurate, from what I can see of the pipe layout, which isn't much, I think the vent pipe goes into the bottom of the header tank. There is a third header tank for the heating and boiler. The cold supply tank to the shower is positioned about 30 inches above the hot supply tank. Phil

 

[terryplumb]

The vent pipe goes in at the top ,its open ended ,goes higher than the top of the tank ,then bends downward into the top of the tank . can you see water coming out of it ? The pipe coming out the bottom of the tank is feeding the hot water cylinder. From the info you have provided so far it would seem that the shower tank ,being higher than the other tank ,supplies the cold at a greater pressure than the hot ,to the pump and onward to the shower. I would suspect the shower rather than the pump. I assume its a thermostatic shower valve ,is that so ? I don't know exactly how the pump crossflow works internally but I would be surprised if it will allow the cold supply to overpower the hot within the pump ,maybe you can contact the manufacturer and ask. With the pump not running ,its entirely possible that it can happen within the mixer valve ,particularly if it has a missing or failed non return valve within it.

 

[Philayl]

Hi, I understand what you ares aying about the pump crossover but I didn't have this problem with either of the RSP50 pumps, it's only arisen since fitting this pump with the newly introduced crossover technology. I have emailed the manufacturer but they are either very slow to respond or are reluctant to. Phil

 

[terryplumb]

You may be right Phil ,maybe you have a duff pump or their " new technology " is susceptible to unbalanced hot / cold pressures. Don't know , does the pump work OK , giving you a good pumped shower experience ? Anything in the installation manual along the lines of its critical that the hot and cold supplies are at identical pressures ?

 

[Philayl]

Will check the installation manual, the shower is ok, it is about the same pressure as the previous ones. If I can't get this sorted soon I will just buy a Stuart Turner pump that doesn't have this new system and throw this week old one on ebay. Phil

 

[byker-1]

Hiya Philayl
(I'm a newbie here)

I have the very same Problem with my New Salamander Pump.
Did you ever resolve this problem?

Thank you for your time.
byker-1

 

[Philayl]

Hiya Philayl
(I'm a newbie here)

I have the very same Problem with my New Salamander Pump.
Did you ever resolve this problem?

Thank you for your time.
byker-1

Hi, I had to exchange the pump for the previous model (RSP50) without the crossover pipe, I found that the introduction of the crossover pipe was a nuisance. If and when this one needs replacing I will probably move to a different make or see if Salamander start to sell one without the pipe. I suggest that you have a look on the site for a link to the forum member called "kvsalamander" and start a conversation with him, he might be able to assist you, he did help me, he works for Salamander. Phil

 

[byker-1]

Hiya Philayl

I would like to thank you for very quick response
and will do as you suggest.
I will post my final outcome on the board
Thanks again
byker-1