power shower - can hot supply be plumbed through attic?

bmcm

Hi guys -

(I'm not a plumber, and apologies if this is an obvious question. I tried searching both here and elsewhere, but didn't find any exact answers...)

Situation is I am replacing an electric shower (cold supply only) with a thermostatic power shower (Mira Vigour T - needs hot supply also). Shower cubicle only relatively recently fitted, and wall newly tiled, so want to disturb it as little as possible. (Why was the hot not plumbed at that time? It should have been - plumber was told to do so, but I didn't check at the time, and now discover he apparently didn't bother :mad:). So minimal disruption option seems to be to route a new hot feed from hot water cyclinder, through attic, and down to shower location. Will need a proper plumber to do this, but (after past bad experiences) want to be sure I know what he should be doing - e.g., can he/should he tee into expansion/vent pipe that already runs into attic from cylinder? Or are there special requirements for connecting into hot supply at cylinder? (NB: I recently installed new insulated cylinder as part of solar water heating system - which, of course, is why I want to replace the electric shower with a pumped one. So, at the cylinder outflow there is a "temperature limiter" of some sort, mixing in cold water if necessary to avoid any risk of scalding. Don't know if that complicates the question of teeing in the hot supply for the power shower...)

Thanks for any pointers/advice.

- Barry.

heinbloed

If the newly installed hot water suply is pressurised then you could tap into that directly.

You wrote:

Or are there special requirements for connecting into hot supply at cylinder? (NB: I recently installed new insulated cylinder as part of solar water heating system - which, of course, is why I want to replace the electric shower with a pumped one. So, at the cylinder outflow there is a "temperature limiter" of some sort, mixing in cold water if necessary to avoid any risk of scalding. Don't know if that complicates the question of teeing in the hot supply for the power shower...)

So you have 1 DHW pipe coming from the cylinder.
It is temperature regulated.

Your plumber propably made no mistake: this pipe can be used for your shower.
Provided it is a.pressurised and b. the pipe work between shower and mixing valve is well insulated and not to long- to avoid pressure loss and temperature loss.

If the pressure is enough than the power shower would be obsolete, a standard shower would be enough. If you and your other household members are happy to use the same temperature than try it out:

Connect a simple garden hose (about the length of the pipe work between mixing valve and shower)and see if the pressure is enough. If you're happy with it.

The existing mixing valve could be exchanged as well for a radio signal controlled mixing valve. With these types of mixing valves the temperature which will be delivered/mixed can be adjusted from the bathroom. Or the kitchen. Or wherever. Delivering the temperature desired at the moment of demand. Connect your washing machine, your dishwasher as well to make the most of it.
Available from most plumbing centers and solar shops.


Otherwise: Yes. you could still run another pipe over the tiles and connect the two with the shower.

Joey the lips

bmcm wrote: »

Hi guys -

(I'm not a plumber, and apologies if this is an obvious question. I tried searching both here and elsewhere, but didn't find any exact answers...)

Situation is I am replacing an electric shower (cold supply only) with a thermostatic power shower (Mira Vigour T - needs hot supply also). Shower cubicle only relatively recently fitted, and wall newly tiled, so want to disturb it as little as possible. (Why was the hot not plumbed at that time? It should have been - plumber was told to do so, but I didn't check at the time, and now discover he apparently didn't bother :mad:). So minimal disruption option seems to be to route a new hot feed from hot water cyclinder, through attic, and down to shower location. Will need a proper plumber to do this, but (after past bad experiences) want to be sure I know what he should be doing - e.g., can he/should he tee into expansion/vent pipe that already runs into attic from cylinder? Or are there special requirements for connecting into hot supply at cylinder? (NB: I recently installed new insulated cylinder as part of solar water heating system - which, of course, is why I want to replace the electric shower with a pumped one. So, at the cylinder outflow there is a "temperature limiter" of some sort, mixing in cold water if necessary to avoid any risk of scalding. Don't know if that complicates the question of teeing in the hot supply for the power shower...)

Thanks for any pointers/advice.

- Barry.

Nnnnnno! You post is a little difficult to read. There is multiple reasons why you cannot do it and i need to disect your post to explain.

"through attic, and down to shower location" If you do this you will end up with negative pressure meaning water will trickle into your shower and your shower will not work

"Will need a proper plumber to do this" To late....Sorry. First plumber should have checked the showers operation you were installing

"can he/should he tee into expansion/vent pipe that already runs into attic from cylinder" No he cant. A lot of bad plumbers do but it starves the shower of water and will most likely cause burn out.


Last bit about the solar does not really matter.Its a temp limiter to prevent the solar overheating your water. Will not really effect your shower as a thermostatic mixer mixes cold at the right temp.


Question: On the wall where the shower valve is what is behind it.

Question. Can you go back to the tile supplier and buy another couple of yards.

Question: Can you change the shower for a feed he provided. He most likely assumed you were fitting a triton T90 or simular so he prob only gave you a cold feed from the attic tank.

bmcm

Thanks for the quick and friendly response!

You wrote:

heinbloed wrote: »

If the newly installed hot water suply is pressurised then you could tap into that directly.

If by "pressurised" you mean fed from mains water pressure, then no, it is not. The hot water cylinder is gravity fed from the cold tank in the attic. (The heating coil to the solar panels is sealed and, I guess, somewhat pressurised, but this has no connection to the hot water supply.) Indeed, there is no (existing) "newly installed hot water suply" at all...

heinbloed wrote: »

Your plumber propably made no mistake: this pipe can be used for your shower.

Just to be clear, there were two separate jobs, done at different times, involving two entirely different plumbers:

1. The hot water cylinder was replaced in the last month, as part of the solar panel installation; I have no concern or complaint about any of this work, but it did not involve any changes to hot water plumbing "downstream" of the hot cylinder. So the outflow from the new cylinder connects (via the temperature limiter I mentioned) to a single, pre-existing, vertical pipe. Upward, this simply goes into the attic and vents into the cold tank - I presume to allow for expansion from the hot cylinder. Downward I presume it feeds all hot water taps in the house.
2. The bathroom was remodelled about a year ago. A bath was removed, and a shower cubicle fitted. The pre-existing electric shower was retained/re-installed at that time, with its pre-existing (unpressurised) cold water feed. I asked the plumber responsible for the required re-plumbing in the bathroom at that time to provide a hot water supply to the shower location, from the old hot supply that was previously feeding the bath (which would otherwise to be simply capped off underfloor), even though this could not be used by the old shower - because I wanted to allow for the possibility that I would subsequently want to do exactly what I am doing now. But when I removed the old shower this week I found there was no trace of this hot water supply I had requested. And of course the old bath plumbing is no longer accessible (without completely remodelling the bathroom again ).

heinbloed wrote: »

If the pressure is enough than the power shower would be obsolete, a standard shower would be enough.

As I say, it is not pressurised, and I do want to install a pumped shower. My question is simply about the correct plumbing of the (new) hot supply to this shower, especially given that it will go back up from the hot cylinder into the attic (so maybe some tendency to air locks?) and given that the pump might (I guess?) run a risk of sucking air back down the expansion/vent pipe, particularly if the (new) shower hot supply was directly teed off this expansion pipe in the attic - which would presumably interfere with showering and possibly (?) damage the pump. (The installation guide with the new shower shows the plumbing taken down and underfloor from the hot cylinder - but it's not clear to me if this is some kind of essential requirement - implying that the supply should not or must not be routed immediately upward from the cylinder, and/or teed off the expansion pipe? But maybe I'm just being paranoid...)

Thanks again - B.

bmcm

You say:

Joey the lips wrote: »

Nnnnnno! You post is a little difficult to read. There is multiple reasons why you cannot do it and i need to disect your post to explain.

Thanks - any help is appreciated here!

"Will need a proper plumber to do this" To late....Sorry. First plumber should have checked the showers operation you were installing

Again, to be clear, there is/was no problem with the pre-existing shower. It works fine. But it is electric, using only a cold water feed. So no benefit from solar heating. So I want to replace that with a new shower unit that takes hot water feed and mixes. I prefer this to be a power shower unit rather than just a thermostatic mixer (unless there is some compelling reason against that?). Which means I need a hot feed, which doesn't currently exist. There was a hot feed to a bath, before the bathroom was remodelling a year ago; and I asked for that to be piped up to the shower location when the bath was removed. But this was not done, so now I will need (somehow) to bring an independent hot supply to the location; and going through the attic is the most accessible route (with minimal disruption to the remodelled bathroom...)

"can he/should he tee into expansion/vent pipe that already runs into attic from cylinder" No he cant. A lot of bad plumbers do but it starves the shower of water and will most likely cause burn out.

Ok thanks, that's exactly what I am wondering about.

Question: On the wall where the shower valve is what is behind it.

Well ... no "shower valve", but where I have removed the electric shower, the wall is tiled (I have so far moved just part of one tile, in search of the expected hot supply...), plasterboard and then an outside cavity block wall. One might conceivably route a new pipe from the attic down between the plasterboard and the outside wall (would need to be some sort of flexible piping); but possibly that would be bad due to risk of freezing?

Question. Can you go back to the tile supplier and buy another couple of yards.

I have not verified this yet, but I believe I can. At least, let's assume I can. But I would still prefer to minimise tile replacement as much as is reasonable. (An option may be to take the new hot supply down from the attic in a visible, chrome, pipe, over the tiling, is that turns out to make more sense at this stage... But I don't want to dismantle the whole wall, shower cubicle and tray in search of the old bath plumbing.)

Question: Can you change the shower for a feed he provided. He most likely assumed you were fitting a triton T90 or simular so he prob only gave you a cold feed from the attic tank.

As I say, the shower I am removing is indeed like this - but that plumber was well aware that I wanted the facility to replace that later with a shower requiring a hot supply, exactly as I am now doing. There was nothing ambiguous at all about that (but that is "water under the bridge" at this stage ). But the whole point here is to exploit the solar water heating in preference to heating electrically, so that can only be done by putting in a hot water supply from the cylinder...

heinbloed

Well explained, bmcm.

I'm afraid there isn't much choice anymore, two un-matching systems can't be combined.
As you said already there is a risk that a pumped shower would suck the system dry and with a non-pumped shower, as Joey-the-lips said, there is a risk that the shower's heating element will burn out.

You will need a second pipe. Better: Check the existing pressure of the mains at the attic. If this is sufficient connect the mains to the cylinder's feed-in to create a pressurised DHW system. If the cylinder's heat exchanger specifications allow for this!
Some cylinders can be fed with pressurised water, others aren't suitable for this.
If the mixing valve can cope with the two pressures (hot, high pressure from the cylinder and cold, low pressure from the attic's tank) you can still install the single pipe shower supply.

So the next step would be to check if the cylinder can cope with pressurised water and if the mixing valve can do so with the existing (different) pressures. Most mixing valves actually can, they start with a min. pressure of 0.5 bar. Which means a difference of 5 meters in height, meassured from the water level (atick tank) down to the mixing valve itself.
But make sure and check the manuals, your plumbers might have provided you with a suitable mixing valve and cylinder.

Would it be possible to pressurise the two, hot and cold?

Check the various shower manufacturers for their "solar" ranges, they might have a suitable shower model available which would fit. Mira springs to my mind. But there you still might need another, second pipe......

Is the shower unit to be placed at a partition wall? Any chance to acess the unit from behind instead above tiles?

bmcm

Thanks heinbloed ...

heinbloed wrote: »

As you said already there is a risk that a pumped shower would suck the system dry and with a non-pumped shower, as Joey-the-lips said, there is a risk that the shower's heating element will burn out.

Well ... I don't actually know for sure under what conditions there is a danger of "sucking the system dry" (that's exactly one of the things I'm wondering about).

I guess I should also have explained that there is already a pumped shower in an en-suite (just plumbed in parallel with the bath hot and cold - there is still a bath in place there). This is completely independent of the (electric) shower I am proposing to replace, and it has operated for years without any problem. But (as far as I know) that hot supply comes underfloor, so does not involve any routing through the attic (upward from the hot cylinder). But it means that I have no worries in general about having a pumped shower (unless having two would cause some additional problem?). I'm just concerned about the question of routing the required new hot supply "overhead".

Studying the install guide again for the "new" shower (Mira Vigour T) what it actually says is:

"Avoid routing the high level hot feed pipe upward to the same level as the cold tank e.g., into the loft space, as air locks may result."

but in fact my cold tank is raised up from the floor of the attic so it would be possible to route a hot feed through the attic while still keeping it below the level of the cold tank throughout. So that sounds OK? Or is it?

As to pressuring the whole hot feed: that might be something to consider, but would (?) mean I would wind up having to replace the other, pre-existing, pumped shower that I mentioned above - even though I'm perfectly happy with it, and all I'm really trying to achieve is to duplicate it in the other bathroom.

So, just to be clear, is the suggestion here that the only way that a hot feed can be successfully taken through the attic (even teeing it at the same level as the hot water cylinder, and keeping it below the existing cold tank throughout) is by pressuring the whole hot water system?

If the mixing valve can cope with the two pressures (hot, high pressure from the cylinder and cold, low pressure from the attic's tank) you can still install the single pipe shower supply.

I'm not sure what "mixing valve" you are talking about. There is no existing mixing valve. Do you mean a new mixing valve that I would fit, in this scenario of pressuring the hot supply, instead of the Mira pumped shower unit that I described above?

Is the shower unit to be placed at a partition wall? Any chance to acess the unit from behind instead above tiles?

The "old" electric unit (that I am removing/replacing) is against an outside wall. So ideally I was hoping to place the new unit in the same place, more or less - since at least there is already a cold supply there, and I might minimise the need for re-tiling. But that said, there is indeed a possibility of moving it around to a partition wall instead, and routing new plumbing from behind that. But that's all kind of secondary: it still needs a new hot supply which would still need to be taken overhead, through the attic...

heinbloed

Quote from your last post:

I'm not sure what "mixing valve" you are talking about. There is no existing mixing valve.

It's this mixing valve we mean, quoting from your first post:

So, at the cylinder outflow there is a "temperature limiter" of some sort, mixing in cold water if necessary to avoid any risk of scalding

And further from your last post:

"Avoid routing the high level hot feed pipe upward to the same level as the cold tank e.g., into the loft space, as air locks may result."

If your hot water supply is pressurised there is no risk of air locks blocking the free movement of water.

Get a plumber in to explain the situation. Systems can be altered, parts changed. Don't expect to peel an apple and finding an orange. Some things don't work.

freddyuk

I have a similar shower to yours and it is fed from a hot supply tee'd off the expansion pipe close to the cylinder. This pipe goes up to the attic, crosses the attic floor for some 30+ feet to the shower below. The main Cold Water tank is 3 feet off the attic floor. A separate cold water feed tank is above the shower (as it should be for a pumped shower) and supplies the cold supply. This works fine. You can use a cold supply off the main cold water tank but if someone empties that tank there is a scalding risk.(hence it is against best practice)

JohnnieK

freddyuk wrote: »

I have a similar shower to yours and it is fed from a hot supply tee'd off the expansion pipe close to the cylinder. This pipe goes up to the attic, crosses the attic floor for some 30+ feet to the shower below. The main Cold Water tank is 3 feet off the attic floor. A separate cold water feed tank is above the shower (as it should be for a pumped shower) and supplies the cold supply. This works fine. You can use a cold supply off the main cold water tank but if someone empties that tank there is a scalding risk.(hence it is against best practice)

The hot water connection at the cold water storage tank should be 30mm above the cold water connection to prevent chance of scalding if supply is lost.

Joey the lips

freddyuk wrote: »

I have a similar shower to yours and it is fed from a hot supply tee'd off the expansion pipe close to the cylinder. This pipe goes up to the attic, crosses the attic floor for some 30+ feet to the shower below. The main Cold Water tank is 3 feet off the attic floor. A separate cold water feed tank is above the shower (as it should be for a pumped shower) and supplies the cold supply. This works fine. You can use a cold supply off the main cold water tank but if someone empties that tank there is a scalding risk.(hence it is against best practice)

You must bear in mind that just because something works does not mean its right and if a plumber installed this s/he would be accountable for possible scalding.

Also just to point out that the thread has got very techanical in nature. I would suggest that the pointers should be kept as close as possible to simple yes and no's for the reason being the op has to translate this to a plumber and some of it may be lost in translation.

freddyuk

Fair point - the cold feed is off the main feed tank and the outlet is below the hot feed but then there is an extra 25 gallons of cold storage in the dedicated tank so doubly safe and the power shower is not impacting the main system supply quite as much with it's own cold supply. Should have explained that better.