Replacing Hot water/CH system in Townhouse

[ln1234]

Would like your advice on our situation:

We live in a townhouse which currently has 3 floors, soon to be 4 with a new loft extension (ground + 3) that is planned. The plumbing system we currently have is as follows.

- Boiler in kitchen (on ground floor)
- Cold Tank in current loft
- Hot Cylinder + pump on 2nd Floor (current top floor)

This system currently supplies 3 bathrooms, but we will be changing this to 4-5 ensuite. What system would you recommend to replace this with considering the tank in the loft will need to be removed? We would require adequate pressure at all shower heads.

I was thinking of making space for the cold tank in the new loft, and upgrading the current cylinder + pump to a higher capacity. Would this work?

Thanks

 

[htgeng]

Get at least 3 quotes on a megaflow cylinder. At least a 145litre version, ideally 170 or 210 if you have the space. You might need to upgrade the water supply pipe to your house too.

Go for a decent boiler too. Your choice of heating engineer will somewhat decide which boiler is installed.

sorry correct terminology is megaflo, but its been somewhat b***rdised into megaflow these days.

 

[ChrisR]

Do a search and you'll see how we go on about measuring your mains VERY thoroughly before you start to think of how to design it.

 

[ln1234]

Thanks for your responses.

I have enquired about getting an upgraded Water Line into the property but have been told it would be very difficult and costly due to the location of the property (on a busy main street). If I were to go for a megaflow system, and assuming my mains water pressure is NOT up to par, could a large 'cold water tank' along with a pump be used to boost the pressure going into the megaflow? i.e. have mains water going into the cold tank and have that pumped into the megaflo via the boiler..

Also, would like to hear from any heating engineers that specialise in these kind of buildings in the London area.

Cheers

 

[ollski]

Thanks for your responses.

I have enquired about getting an upgraded Water Line into the property but have been told it would be very difficult and costly due to the location of the property (on a busy main street). If I were to go for a megaflow system, and assuming my mains water pressure is NOT up to par, could a large 'cold water tank' along with a pump be used to boost the pressure going into the megaflow? i.e. have mains water going into the cold tank and have that pumped into the megaflo via the boiler..

Also, would like to hear from any heating engineers that specialise in these kind of buildings in the London area.

Cheers

Yes it should be ok with a break tank, but mighty expensive and quite specialized.

 

[htgeng]

This one was done in a 4 storey townhouse in W2. A 250litre megaflow and new boiler in basement. Send me an email if you want more info.

http://img.photobucket.com/albums/v464/htgeng/misc/atagmegaflow1.jpg

 

[ChrisR]

htgeng -curious about what you did with the discharge pipe (being in a basement), and what pump is that - is it a "pump set"?

In1234 sure you can do it, in principle. Here's one example tale Start at "tale of caution" 2/3rds down

Pump position is important, so is the diameter of the pipe from the cistern(s) to the pump. So is the size of the water store - you can empty a big one quickly. Pump noise may be an issue- garages can be ideal to put them in but if the cistern's in the loft and it needs a new pipe that can be a time consuming job. The tank could go in the garage of course, for example. Can be a problem if the top tap is more than say 11 metres above the pump.
Cylinder position not usually a problem though it's advisable to connect your cold (as well as hot!) tap supplies to it.
You really don't want your wc's on the pumped supply though because of noise at night. That means separating CW supplies which won't be simple (unless the wc's are already on the mains).

By the way which part of London are you?

 

[ln1234]

htgeng, ChrisR - this is exactly the type of system i'm looking for. I forgot to mention that we have an ol coal vault at basement level, which is located just outside the property (under the pavement) that could be used to house everything. I understand that it's a complex system to design, but if you could tell me what pitfalls to watch out for, that would be great.

We are located in SW1, and would probably need something similar to the property in WC2. How do I email you on here for more details? my email is [email protected] - could you send me details of this system?

- Which boilers can have an extended flue? i.e. from basement, up 4 storeys?
- Are there any diagrams for a system like this (including CH), with recommended pipe sizes etc?

Cheers

 

[htgeng]

htgeng -curious about what you did with the discharge pipe (being in a basement), and what pump is that - is it a "pump set"?

it was actually a basement with drive in garage, so discharge was at ground level into a gully. Its a mains pressure system there is no pump in the setup. The chap had the supply upgraded to 32mm and I ran 28mm to the megaflow. The hot pressure even to top storey(even through existing pipework) is amazing and he is very happy with the end result.

 

[chrishutt]

htgeng, you've got an isolating valve on the cold mains into the Megaflo which could isolate the Megaflo from the Pressure Release Valve, which is further upstream, where the check valve, etc. is.

I know the temperature relief valve on the cylinder would provide a second line of defence against excess pressure (albeit at a higher pressure setting) in the event of the isolating valve being closed, but it still strikes me as, well, not good practice.

 

[htgeng]

htgeng, you've got an isolating valve on the cold mains into the Megaflo which could isolate the Megaflo from the Pressure Release Valve, which is further upstream, where the check valve, etc. is.

I know the temperature relief valve on the cylinder would provide a second line of defence against excess pressure (albeit at a higher pressure setting) in the event of the isolating valve being closed, but it still strikes me as, well, not good practice.

I can't verify atm as I don't have documents to hand, but Im certain that the first prv is effectively isolated from the cylinder by a double check valve anyway. I have seen some cylinders where the double check is actually built into the cold feed inlet on the cylinder.

 

[chrishutt]

I've just checked the notes from the Vaillant unvented course I did, and they certainly show that the Pressure Release Valve (or Expansion Valve) should be between the cold inlet on the cylinder and the check valve.

Otherwise it wouldn't function at all, and all expansion that wasn't accommodated internally (Megaflo air bubble - prone to absorption) would have to discharge via temperature relief valve. I'm afraid your installation is in need of some remedial work.

 

[bripl]

not one to complain but
do you own a drill ?
do you own benders?
how about lagging?
no secondary ret?
just a few points to consider tidy job otherwise

 

[ollski]

From the bs:

The expansion relief valve shall be fitted on the supply pipe close to its connection to the heater without any intervening valves.

Normally goes stop cock, strainer, pressure reducing valve, check valve, expansion relief

 

[htgeng]

From the bs:

The expansion relief valve shall be fitted on the supply pipe close to its connection to the heater without any intervening valves.

Normally goes stop cock, strainer, pressure reducing valve, check valve, expansion relief

wow thanks for all the kind words - ivory towers and all that. All points made were considered during installation. I'd love to see pictures of some of your work lads!

do you own a drill ?
yes, several
do you own benders?
yes
how about lagging?
picture was taken before lagging
no secondary ret?
was not required by customer.