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

 

[stevetheplumber]

you learn some thing every day i would have said it wasnt possible but seen like that its obvious

 

[Chalked]

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

Secondary Return Schematic

who makes a a heat exchanger like that? Interesting way to do it tho.

 

[chris watkins]

What you are proposing to install is IMHO over engineered for your requirements, you need to sit down with an experienced plumber who can run you through all the options. They will not be to enamoured if you ask them to start second fixing onto somebody else's 1st fix, they will charge you a premium for the aggro.
If of course you want to DIY then would strongly recommend you pay for pro advice there are still good people out there, it will be cheaper in the long run take our word on it.
Good Luck

 

[Ermintrude]

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

BSS industrial? School, hospital, offices. You could generate steam and fit a few flash heaters if site is big enough .

What did you want the system to achieve ? - it's a straight up question write down what you want and what you would like, it's a design brief for fitter,helps a lot. You can evaluate financial and mechanical merits / pitfalls. ACV tech could help u once u have a brief.

 

[Star Cruiser]

What you are proposing to install is IMHO over engineered for your requirements, you need to sit down with an experienced plumber who can run you through all the options. They will not be to enamoured if you ask them to start second fixing onto somebody else's 1st fix, they will charge you a premium for the aggro.
If of course you want to DIY then would strongly recommend you pay for pro advice there are still good people out there, it will be cheaper in the long run take our word on it.
Good Luck

Chris, that's exactly my thinking re a plumber picking up a "botched" part first fix installation.... DIY is maybe an option, but I definitely need to find someone to help me on the design side. Any recommendations of where to start for that advice?

 

[Star Cruiser]

BSS industrial? School, hospital, offices. You could generate steam and fit a few flash heaters if site is big enough .

What did you want the system to achieve ? - it's a straight up question write down what you want and what you would like, it's a design brief for fitter,helps a lot. You can evaluate financial and mechanical merits / pitfalls. ACV tech could help u once u have a brief.

Thanks for your advice. The BSS industrial stuff is obviously a large installation. I thought it might be useful for my requirements albeit on a smaller scale?

I will write a bit of background and design requirements paper and I'll post later to see what people think.

 

[Star Cruiser]

I've drafted up this design brief. What have I missed off that will be needed?

Domestic Plumbing System:

Background
A timber frame, 3 storey, 5-6 bedroom house in the course of construction, currently at first fix stage. The house is located in the North East, near the North Pennines, high up at 300 metres (1,000 ft). It gets quite cold and windy and there are periods when the electric is out. The fabric will be well insulated, U-Value wise:

Walls 0.12 w/m2K
Roof 0.15
Ground Floor 0.12
Windows 1.4-1.7

SAP Assessment
A desktop SAP calculation has predicted:

Final SAP Rating of 89 (Band B)
Space Heating 21,568 kWh/year
Hot Water 2,677 kWh/year

It just misses out on Band A as it is marked down for having a MHRV system. If we didn’t install that and just fitted normal extractors, it would be Band A. That’s how stupid SAP is.

Heating
Water underfloor heating on the ground floor only within a flow screed and ceramic tile finish.

A whole house Mechanical Heat Recovery ventilation System (MHRV) has been fitted as part of the first fix – solid spiral ducted. This is a [DLMURL="http://www.allergyplus.co.uk/wp-content/uploads/2011/01/KWLC-650-Install.pdf"]Helios KWLC 650/WW[/DLMURL] with a water battery heater fitted. This will top-up the incoming supply air if the heat exchanger cannot fully heat.

Bathroom Towel Rails
These have been first fix plumbed in 15mm copper. These will provide the heat needed in the bathrooms to replace the air extraction side and also balance some heat around the rest of the house via the MHRV.

Hot Water Supply
Required to:

Ground Floor Kitchen, Utility and Cloakroom WC
First Floor Main Bathroom and En-suite
Second Floor Bathroom

Some of the runs are 15-20 metres, so thinking was to have a hot water loop to minimise draw off waste.

Solar Thermal and PV
2 x 10 Navitron 70mm solar thermal tubes fitted to south west roof @ 38 degree pitch. To be plumbed in.

4kW solar PV panels fitted to south west roof @ 38 degree pitch. Immersun unit to be fitted to divert excess generation to thermal store immersion.

Proposal
Natural gas is available, although not fitted as yet.

Thermal store (size tbc) to be installed in garage and to take solar inputs and feed all hot water needs. Gas boiler will top-up if needed, although it is hoped the store can feed most needs with 2-3 days of stored reserve to see us through the cold snaps or when solar feeds are poor.

Thermal Store Inputs:
1. Solar Thermal (2 x 10 Navitron 70mm tubes)
2. Excess Solar PV via electric Immersion.

Thermal Store Needs to Feed (via boiler booster if needed):
1. Hot Water Loop to all tap outlets.
2. MHRV Water Heater Battery.
3. Underfloor Heating System.
4. Bathroom Towel Rails

Gas Boiler
This will top-up the thermal store (if needed) and see us through cold periods. The Rinnai booster boilers, which only heat up water supplied via thermal store if needed, are of interest. Would prefer a tried and tested boiler if this can fit in with the system design.

 

[Ermintrude]

Pretty comprehensive pack. Send to ACV as they have good thermal stores , the will spec system for you.

 

[Star Cruiser]

Pretty comprehensive pack. Send to ACV as they have good thermal stores , the will spec system for you.

I have just spoken with ACV. They are getting my local rep to contact me and he will visit site and look over. Hopefully this is a good start as he's bound to know local Engineers who can help.

 

[Star Cruiser]

Very little feedback on my Design Brief? Please let me know if I have missed anything or if there are some good thermal store / boiler suppliers I can approach.

Ermintrude, thanks for your feedback and suggestion. I have a site meeting with ACV Rep next week.