Plumbing Problems – Hot Water Loop

[Star Cruiser]

Hello UKPF. I'm a new member, in the process of trying to self-build a house. I hope I have come to right place for some good advice and help. I have a potential problem with my first fix plumbing hot water loop. I’ve since fell out with the plumber (long story) who undertook this and it looks to me that he maybe didn't know what he was doing in terms of my request for a hot water loop.

It’s not easy to describe, but here goes. Instead of plumbing a continuous loop to all the hot water points and then having a single return pipe, he has Teed off where needed with both a Hot Water Feed (22mm) and Hot Water Return pipe (15mm). Some of these Tees are a good few metres in length and I wonder if this method will work or not? I’m wondering if this will balance out ok?

I've drawn up a crude sketch of what I think is going on:

https://www.dropbox.com/s/mssw7i02msu0309/Photo 03-09-2013 10 46 24.jpg

I don’t want the original plumber back, so I need to confirm if this will work or not or whether I need to alter.

Thanks in advance for any advice or help.

 

[Ermintrude]

Can't see picture,?

 

[chris watkins]

Looks over kill on the number of connections between the flow & return depending on how far away each tee is from the terminal fitting.
More of a worry is the fact you show a thermal store as the source of the hot water ? These are instantaneous water heaters & as such do not normal have secondary return systems installed.
I would be inclined to find yourself a good plumber or design engineer who can produce a layout & equipment schedule for you before things go wrong.

 

[Star Cruiser]

Can't see picture,?

It seems my privileges in terms of posting links and urls are restricted as I'm a new member.

 

[chris watkins]

Hope this helps.

 

[Star Cruiser]

Thank you for sorting the photo Chris and for your info.

My plan is for the thermal store to have solar thermal feeding it when the sun is good and also excess solar PV (4kW) via an electric immersion controlled by a immersun unit. The hot water supplies will be fed through a top-up gas boiler from the thermal store. Rinnai do a gas boiler range which will only top up the heat required from the thermal store supply, which is supposed to save gas consumption. No top-up required = no gas used. I'm not sure of there are other manufacturers of such boilers?

I really cannot believe what the previous plumber has done. Your advise is good, but like all thing it's finding a good plumber / designer who now willing to help me sort my situation.

 

[chris watkins]

Alpha boilers SolarSmart 100 do something similar to what you describe but as I say with both systems the water is classed as instantaneously heated so you will not be able to have a secondary hot water system as drawn. There are other ways of resolving the problem, find someone who knows what they are doing !!
Good luck.

 

[Ermintrude]

The circulator is going to waste as much energy as you would just dumping water. Why are you going PV then immersion? Why not photo thermal directly ? Normally unless the branches are 3m or more only main leg is circulated and rest is dead legs . 3m of 15mm contains 0.002 m3 of water but will radiate at almost same rate as 22mm tube. Rationalise system, problems will be caused and amplified by a badly over specified system.

 

[SimonG]

Secondary return on a thermal store???????

 

[Star Cruiser]

Why can I not reply to a post with a quote containing a url? That's a bug which needs sorting out on here!

 

[Star Cruiser]

Chris, I cannot quote your post as I'm stopped from replying to anything caontaining a url.

I really need to get a basic understanding of what I require before I attempt to use a plumber and get my fingers burnt again. I was hoping I may get some advice on the best way to go about solving my installation on here. Can my layout be easily adapted to form a hot water loop?

 

[Star Cruiser]

The circulator is going to waste as much energy as you would just dumping water. Why are you going PV then immersion? Why not photo thermal directly ? Normally unless the branches are 3m or more only main leg is circulated and rest is dead legs . 3m of 15mm contains 0.002 m3 of water but will radiate at almost same rate as 22mm tube. Rationalise system, problems will be caused and amplified by a badly over specified system.

Hi, can you explain photo thermally direct? Not sure what that is?

I could really throttle the plumber. He was adamant that he knew what he was doing, when it now appears he was winging it. I would like to rationalise the system as best I can!

 

[Star Cruiser]

Secondary return on a thermal store???????

Hi Simon, what would you suggest?

 

[Dotty]

Why can I not reply to a post with a quote containing a url? That's a bug which needs sorting out on here!

It's not a bug at all but a security feature. Once you hit 10 posts you'll get a few more priviledges.

 

[SimonG]

All the thermal stores I've seen produce instant hot water and you don't have a store of hot domestic water to circulate. For your secondary return you will need a store of water so either vented or unvented.

 

[SafeGasInstall]

in what stage is the job now ?

 

[Star Cruiser]

It's not a bug at all but a security feature. Once you hit 10 posts you'll get a few more priviledges.

Thanks. I thought it might get better when I had a few posts to my name.

 

[Star Cruiser]

in what stage is the job now ?

We are at first fix stage, but I want to get the plumbing sorted so I can at least plasterboard some first floor bedrooms out and move in to the house before the winter.

 

[Star Cruiser]

All the thermal stores I've seen produce instant hot water and you don't have a store of hot domestic water to circulate. For your secondary return you will need a store of water so either vented or unvented.

Some of the runs are quite big, so the idea of the hot water loop was to insulate this well and minimise the draw-off waste before hot water arrives.

 

[Star Cruiser]

On page 6 of this document (under Installation) is a schematic which looks useful to my installation. (Apologies but I haven't got the software to cut and paste directly at the moment). I would obviously only need 1 boiler!

http://www.bssindustrial.co.uk/uploads/docs/666.pdf

 

[SafeGasInstall]

We are at first fix stage, but I want to get the plumbing sorted so I can at least plasterboard some first floor bedrooms out and move in to the house before the winter.

so is not to late then ,

list your location and some one who is a member here will be happy to help you with the job
[DLMURL="http://www.ukplumbersforums.co.uk/im-looking-plumber-gas-engineer/"]I'm looking for a Plumber or Gas Engineer[/DLMURL]

 

[Ermintrude]

Get a run of the mill boiler, ideal Baxi valliant. As good as any other , in future u will regret getting a boiler that's "special" as no one can fix it, parts are 3-5 days and its probably going to save u a few quid now also.

 

[SafeGasInstall]

Get a run of the mill boiler, ideal Baxi valliant. As good as any other , in future u will regret getting a boiler that's "special" as no one can fix it, parts are 3-5 days and its probably going to save u a few quid now also.

just what i was thinking too

 

[Chalked]

If your still at first fix stage all is not lost. If you want circulated hot water I would get a twin coil pressurised cylinder. One coil for the gas boiler ( just get a vaillant or equivalent) and one coil for solar.
if your wanting to maximise your solar you could fit a thermal store on the solar side.

 

[BLOD]

hw return with a thermal store is possible, it's whether you need it.

Secondary Return Schematic