Raks

Remote Place for the Combi

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I am considering to put my combi in a small old utility area at the side of the house. Because we are changing the layout, now we can't access to this old utility area from inside the house but from the garden side entry only

As far as I see with the new boilers every thing is remote controlled and monitored. My question is how convenient is it to put a combi in a remote area like this? I am not that lazy to walk but in a cold winter night going around the building  not something that I like if I have to do often :)

 

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As long as you can get to it for servicing it is fine.  If the area is unheated, lag all the pipes properly.  The nearer to kitchen and bathroom the better.

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1 hour ago, Mr Punter said:

As long as you can get to it for servicing it is fine.  If the area is unheated, lag all the pipes properly.  The nearer to kitchen and bathroom the better.

Still part of the house and its a warm area.  Fully accessible for service or checking. 
a 7-8 meter main pipe will run to the manifold in the house  first (under the staircase) then  8 radiators will get their return and supply from this manifold separately so full room by room control possible. Same for the hot water plumbing, three manifolds (kitchen, bath and ensuite) all getting their hot water directly from the combi then the wash basin, shower or the kitchen sink gets their from the manifold. 
 

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Expect a long delay in getting premium hot water out of the hot taps, especially the furthest away. 
Other than that, no issues whatsoever. 
Check with the boiler manufacturers installation instruction to see if the boiler has an in-built frost thermostat or whether it is down to you to buy and install one. 
If the room is prone to super low temps at the worse part of winter, fit an electric tubular heater with its own frost thermostat. 
Set the boiler frost stat to 7oC and the tubular heater stat to 10oC. 

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35 minutes ago, Nickfromwales said:

Expect a long delay in getting premium hot water out of the hot taps, especially the furthest away. 
Other than that, no issues whatsoever. 
Check with the boiler manufacturers installation instruction to see if the boiler has an in-built frost thermostat or whether it is down to you to buy and install one. 
If the room is prone to super low temps at the worse part of winter, fit an electric tubular heater with its own frost thermostat. 
Set the boiler frost stat to 7oC and the tubular heater stat to 10oC. 

The problem is where ever I move the combi some of the  hot water taps  or showers would be at least 10-15 m away.

Other then a good pipe insulation, is there any other method or technology to minimise this hot water delay  because of the pipe length ?

 

 

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Not really, with a combi. 

You can take the edge off a little with a pre-heat aka warm-start combi where the boiler fires intermittently to keep the DHW plate heat exchanger at premium temperature, thus staving off the time you lose waiting for the boiler internals to heat up from cold ( eg the time lost waiting for the premium heat delivery temps to be achieved and output from the combi DHW outlet. 
Bottom line is NEVER have 22mm DHW pipe work from the boiler to the outlets.  
 

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10 minutes ago, Nickfromwales said:

Not really, with a combi. 

You can take the edge off a little with a pre-heat aka warm-start combi where the boiler fires intermittently to keep the DHW plate heat exchanger at premium temperature, thus staving off the time you lose waiting for the boiler internals to heat up from cold ( eg the time lost waiting for the premium heat delivery temps to be achieved and output from the combi DHW outlet. 
Bottom line is NEVER have 22mm DHW pipe work from the boiler to the outlets.  
 

How  about Vaillants's or Veismann's "storage combi"s?

Or  is there a way to circulate the water in the pipe  intermittently if the temperature drops. (like using a loop pipe  connection as a  small hot water storage)

 

And on the pipe size, even if I have 3 areas with their own manifolds, still no need for 22mm?

3 areas/3 manifolds : kitchen, bathroom, ensuite. 15mm pipes will run to the tabs/showers in these areas from the manifold  in this area but  I was considering a 22mm with  2 "T connection" to supply DHW to these manifols. IS it better and enough to run everything 15mm?

 

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15mm inlet on the combi = total waste of time putting 22mm on the outlet. ;)  

The only reason you’d go to 22mm would be to reduce resistance over a VERY long run.
 

To be honest, utilising manifolds with a remote combi is not a very good idea IMO as you’re adding a huge amount of dead leg to each outlet, particularly the basin tap ( high frequency / low volume use ) which will be a PITA. If you want some divisibility then you could do 2x 15mm runs from the combi 1x 1st floor 1xground floor / whatever best divides the system, and just have an isolator ( FULL BORE ) at the combi for each run. 

 

The Vaillant 938 is a fantastic boiler with IIRC a 15L pre-heat cylinder ( actually it’s 2x 7.5’s for less physical space requirements ) and is comparable in DHW delivery to a 200L UVC. It’s only Ach’s heel is it’s still only a 15mm inlet & outlet, but with a good cold main you really can’t tell.

The time from opening an outlet to actually getting premium temp DHW is massively reduced as it’s always got that buffer ready to go, so definitely a contender for anywhere where longer DHW runs will end up causing inconvenience.

 

Veismann combis seem to have a good following but I can’t really say I’d rate them over the Vaillant if I’m honest. Guess I’m biased because I’ve fitted so many of the Vaillant units without an ounce of grief. 
 

Adding a DIY hot return to a heat store boiler will, I’m pretty sure, void the warranty. Ring the various manufacturers to ask, but I think the only heat-store combi I’ve ever seen with a tank and a hot return tapping was the Arirton 27 Plus ( a steaming bag of shit on a good day though, and I’d only fit one for someone I disliked ). The 27 Plus was the old model, they may have renamed it since I saw one of them last. 
 

Vaillant 938 all the way if it was me.  

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@Nickfromwales

 

What is your rough estimate of the overhead of a preheat tank on bills?

 

I have always run mine in Eco mode with that off (big Worcester Bosch Combi), and my longest pipe run is I guess around 12-14m.

 

Ferdinand

 

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4 minutes ago, Ferdinand said:

@Nickfromwales

 

What is your rough estimate of the overhead of a preheat tank on bills?

 

I have always run mine in Eco mode with that off (big Worcester Bosch Combi), and my longest pipe run is I guess around 12-14m.

 

Ferdinand

 

Very little when it’s designed in. 
The Vaillant has the 2x PH tanks fully encapsulated in EPS to minimise losses. 
Would be greater if added retrospectively or done on an UVC / other, but Vaillant have had to do that to maintain ERP rating. 
 

Honest answer would be run yours for a quarter and compare bills. 

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2 hours ago, Nickfromwales said:

15mm inlet on the combi = total waste of time putting 22mm on the outlet. ;)  

The only reason you’d go to 22mm would be to reduce resistance over a VERY long run.
 

To be honest, utilising manifolds with a remote combi is not a very good idea IMO as you’re adding a huge amount of dead leg to each outlet, particularly the basin tap ( high frequency / low volume use ) which will be a PITA. If you want some divisibility then you could do 2x 15mm runs from the combi 1x 1st floor 1xground floor / whatever best divides the system, and just have an isolator ( FULL BORE ) at the combi for each run. 

 

The Vaillant 938 is a fantastic boiler with IIRC a 15L pre-heat cylinder ( actually it’s 2x 7.5’s for less physical space requirements ) and is comparable in DHW delivery to a 200L UVC. It’s only Ach’s heel is it’s still only a 15mm inlet & outlet, but with a good cold main you really can’t tell.

The time from opening an outlet to actually getting premium temp DHW is massively reduced as it’s always got that buffer ready to go, so definitely a contender for anywhere where longer DHW runs will end up causing inconvenience.

 

Veismann combis seem to have a good following but I can’t really say I’d rate them over the Vaillant if I’m honest. Guess I’m biased because I’ve fitted so many of the Vaillant units without an ounce of grief. 
 

Adding a DIY hot return to a heat store boiler will, I’m pretty sure, void the warranty. Ring the various manufacturers to ask, but I think the only heat-store combi I’ve ever seen with a tank and a hot return tapping was the Arirton 27 Plus ( a steaming bag of shit on a good day though, and I’d only fit one for someone I disliked ). The 27 Plus was the old model, they may have renamed it since I saw one of them last. 
 

Vaillant 938 all the way if it was me.  

Very helpful thank you .🙏

 

Ok I will go for 938. I was considering manifold system to install a central room by room temperature control system with out TRVs.

 

For an other property 3 bed+1 bath but with a potential loft/ensuite (in few years maybe): Is it too much to put a 938 now or are they efficient enough even for smaller properties?

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2 hours ago, Nickfromwales said:

Very little when it’s designed in. 
The Vaillant has the 2x PH tanks fully encapsulated in EPS to minimise losses. 
Would be greater if added retrospectively or done on an UVC / other, but Vaillant have had to do that to maintain ERP rating. 
 

Honest answer would be run yours for a quarter and compare bills. 

 

Cheers.

 

f

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21 hours ago, Raks said:

Very helpful thank you .🙏

 

Ok I will go for 938. I was considering manifold system to install a central room by room temperature control system with out TRVs.

 

For an other property 3 bed+1 bath but with a potential loft/ensuite (in few years maybe): Is it too much to put a 938 now or are they efficient enough even for smaller properties?

Ah, my apologies. I thought you were manifolding the hot and cold water system. D’oh!! 😖. FYI I do that routinely on my projects. 😉 hence my knee jerk response. 
Manifolds for the heating will be fine. 👍 

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Just now, Nickfromwales said:

Ah, my apologies. I thought you were manifolding the hot and cold water system. D’oh!! 😖. FYI I do that routinely on my projects. 😉 hence my knee jerk response. 
Manifolds for the heating will be fine. 👍 

well.. I was considering manifold for hot/cold water as well :) 3-4 port ..one in bathroom, one in kitchen but each got supply directly.

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On 04/12/2019 at 07:29, Raks said:

well.. I was considering manifold for hot/cold water as well :) 3-4 port ..one in bathroom, one in kitchen but each got supply directly.

If they get supplied directly, from source, and on 15mm supplies then probably not that much more of an impact tbh. 
If you have separate isolatable runs from source anyway, is there any actual need for the manifolds ? 🤔

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1 hour ago, Nickfromwales said:

If they get supplied directly, from source, and on 15mm supplies then probably not that much more of an impact tbh. 
If you have separate isolatable runs from source anyway, is there any actual need for the manifolds ? 🤔

OK, as I understand all pipes would be 15mm for hot & cold water, I will check your previous post regarding to the 15 or 22mm for the CH. 🙄 

 

I first came across these "plumbing manifolds" while looking for manifolds for radiators :

https://www.heatdirect.co.uk/emmeti-multiplex-sanitary-manifold-2099.html?gclid=EAIaIQobChMI4sT_1vqe5gIVwkPTCh1SlAiBEAQYBiABEgLOR_D_BwE

 

I like the idea of  point-to-point one piece pipe, so less problem points when running all the pipes behind  walls in a new ensuite:

 

And then for a studio, the manifold is in a wall box which can be accessed without entering the studio,  so if something goes wrong while tenant away, its easy to cut off the supply for any of the points. Of course these can be done without a manifold  as well but this kind of one pieces solutions are  seems compact and easy to implement depends on your planning. By the way, I didn't know that but ii was told the manifold plumbing is the norm in some of the European countries.  

 

Everything is positive in these marketing videos but whats your main concern about the plumbing manifold in these kind of installations?

 

 

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On 02/12/2019 at 21:21, Nickfromwales said:

Expect a long delay in getting premium hot water out of the hot taps, especially the furthest away. 

 

I had this issue in our bathroom, mostly solved by using a thermostatic mixer on the supply to the toilet, set 30degreesC to protect it from damaging the cistern.

 

By the time you've flushed the toilet, got yourself in order and are ready to wash your hands the hot water has been purged and not wasted drawing it off in the sink.

 

Added bonus is there is never any condensation on outside of the toilet cistern.

 

I will do the same on our next bathroom install.

 

 

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1 minute ago, JFDIY said:

 

I had this issue in our bathroom, mostly solved by using a thermostatic mixer on the supply to the toilet, set 30degreesC to protect it from damaging the cistern.

 

By the time you've flushed the toilet, got yourself in order and are ready to wash your hands the hot water has been purged and not wasted drawing it off in the sink.

 

Added bonus is there is never any condensation on outside of the toilet cistern.

 

I will do the same on our next bathroom install.

 

 

 

What happens if you need to double flush (or even triple flush!) a stubborn lurker?  Surely it will get poached?

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3 minutes ago, Mr Punter said:

 

What happens if you need to double flush (or even triple flush!) a stubborn lurker?  Surely it will get poached?

 

Not really, being limited to 30degC is only comparable to a hot summers day.

You could do 25C and as long as your room isn't that hot it'll work.

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Just simply adding more stagnant cold water volume between the boiler and the hot outlet. It's only really problematic for the basins / sinks where high frequency / low volume consumption occurs.

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14 hours ago, JFDIY said:

 

I had this issue in our bathroom, mostly solved by using a thermostatic mixer on the supply to the toilet, set 30degreesC to protect it from damaging the cistern.

 

By the time you've flushed the toilet, got yourself in order and are ready to wash your hands the hot water has been purged and not wasted drawing it off in the sink.

 

Added bonus is there is never any condensation on outside of the toilet cistern.

 

I will do the same on our next bathroom install.

 

 

Not as crazy as it first sounds for sure. Especially when you have freezing cold water entering a porcelain cistern in a warm house. 
TBH, if I was providing for that remit I would fit a local accumulator ~30L to blend ambient temp water with the incoming cold to provide some uplift. 
Or tank feed the loo. 

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