Help speccing a new heating/dhw system

[Biggles..]

Agree with the point that for point of use hot water through something like a plate heat only that avoids stored water could be an issue, firstly common to all solutions is your current flow rate.
The other issue that was mentioned is that of the gas supply required to heat a stand alone plate, a standard domestic gas supply/meter would only do about 27lpm flow at a 35deg rise,again not ideal if your running multiple outlets.

Stored water is likely to be a must, that's now wether you opt for thermal store or unvented.
Current thermal store market is so expensive, the only one I would recommend is DPS, but since spec flue have taken over their prices have nearly tripled making them unrealistic.

Each to there,own, lots of solutions but some limiting factors with cost I presume being one of the greatest.

 

[Agile]

Two years ago in December I lost my heating and hot water, it was the very very cold winter when we had record snow and low temps if you recall. My house is 1902 built with part single glazed windows and only partially insulated (at the time)

I called around countless people including BG and NPower, they were so confused by my set up that they were not prepared to venture what the issue actually was. At that time I myself had no idea how my system worked, I had never taken an interest so could not explain it.

I dont recall that you ever called me!

Tony

 

[ALEC1]

a key bit of information will be what is the maximum demanded flow rate.

You won't want to use the showers when you are filling a bath (will you) so to supply everything at once is not really the right objective.

If you have 4 showers at 10l/m then 40l/m must be available into the hot and cold system.

What is the resistance of the fittings? This will determine the size of water booster you require...

What you are seeking is not complex or involved..it is essentially a boiler a controller (several of which control the DHW circulator) a cylinder and a boozer set.....to make sure this is seamless then specify one from the boiler manufacturer...that way you get the after sales support that you missed in the old set up..

 

[SimonH2]

Two years ago in December I lost my heating and hot water, it was the very very cold winter when we had record snow and low temps if you recall. My house is 1902 built with part single glazed windows and only partially insulated (at the time)

I called around countless people including BG and NPower, they were so confused by my set up that they were not prepared to venture what the issue actually was. At that time I myself had no idea how my system worked, I had never taken an interest so could not explain it.

For my flat, although I do most of the maintenance, I drew up a small technical file for anyone working on the system (should only ever be someone doing the boiler). It's got a drawing of the hydraulic arrangement - not complex, but does have two extra TMVs in it; an electrical diagram - again not complex as it's only the boiler, a single cylinder stat, and a CH pump; a photo of the store and associated plumbing with all the items identified; a description of the system; and setup instructions. There' s a copy of this tucked in behind the boiler where anyone servicing it can see it, and I've given a copy to the people I have a service contract with - which has gone in their file and so can safely be assumed won't be looked at again !

So there should be no excuse whatsoever for anyone not understanding it, and even less excuse if someone comes along and start modifying it because they think it's wrong - if they do that, then they'll find life pretty uncomfortable.

There's also a smaller sheet with operating instructions for the tenant - which only covers lighting the boiler, setting the time clock for the CH, and setting the TRVs - and which includes a warning that nothing else must be altered (the cupboard with the store is 'sort-of' locked with one of those splined key bolt thingies).

 

[indus]

Thanks for the input guys.

I still haven't got around to measuring the pressure, I'll try and get that soon and then post back.

May I ask,

1) Would there be any potential problems if I located my Mega Flows (one or two) in the loft and had my boilers downstairs on the ground floor? Does this in anyway compromise the system?

2) I've read in a few places that a Grundfos home booster type pump is best loacted in a basement. Is that true and if so why?


Thanks again for all the help

 

[SimonH2]

1) Would there be any potential problems if I located my Mega Flows (one or two) in the loft and had my boilers downstairs on the ground floor? Does this in anyway compromise the system?

I don't think it should make any difference. Further, with an unvented tank, it can go anywhere (subject to support requirements - water is heavy).

2) I've read in a few places that a Grundfos home booster type pump is best loacted in a basement. Is that true and if so why?

Quite probably. If you think about it, if you have low pressure, the last thing you want to do is subtract another 20 to 30 foot of head from it. 30 foot is 1 bar.
So put the booster pump where the pressure is highest - which means at the lowest point possible. That way, the mains can push the maximum amount of water into the booster pump. After that, you are in control of everything, and you can juggle flows, pipe sizes, and pump pressures to get whatever pressure you want - subject only to the maximum flow the mains will deliver at the inlet to the pump.

Actually, I suspect the pump is "suck" a bit, but ideally you want to avoid that as you can cause a number of issues - not least, cavitation in the pump which can be a) noisy, and b) quite damaging.

 

[Agile]

Simon, whilst the best place is in the basement, I dont think you understand how they work!

Have you ever installed or repaired one?

Your description would not comply with the Water Regulations!

Tony

 

[indus]

Two years ago in December I lost my heating and hot water, it was the very very cold winter when we had record snow and low temps if you recall. My house is 1902 built with part single glazed windows and only partially insulated (at the time)

I called around countless people including BG and NPower, they were so confused by my set up that they were not prepared to venture what the issue actually was. At that time I myself had no idea how my system worked, I had never taken an interest so could not explain it.

I dont recall that you ever called me!

Tony

I wasn't on this forum at the time Tony! If I had been perhaps I wouldn't have suffered quite the way I did.

 

[SimonH2]

Simon, whilst the best place is in the basement, I dont think you understand how they work!

It's a pump, the physics of which are fairly well known.

Have you ever installed or repaired one?

No, and I've never claimed to have done.

Your description would not comply with the Water Regulations!

Says one of the many who haven't offered any better description

OK, so it seems they are an open vent setup - I assume a ballcock in a small tank and then the pump from there. Makes no difference to the basic physics - if you put it in the attic instead of the basement then you've lost around a bar before the pump inlet and so you've reduced the flow by that much. If your pressure is so low that you need such a pump, then it's a fair bet that losing a bar is a big deal.

 

[Dan Robinson]

Homebooster is recommended in the basement or groundfloor for noise reasons as well as potential flood damage in the event of a problem. They are just a CWS cistern with a pump module. You can bolt another 200 litres of cold storage to the side as well.

 

[Biggles..]

Theyre actually based around an accumalator not a constant pressure boost pump from a break tank.
It's all about charging to a pressure above that of the system requrements and then when your getting close to your required pressure minimum charging it back up.

View media item 19282
Thermal store an homebooster,runs 5 showers and 2 baths plus multiple sinks at 2bar with minimum of 10lpm at eac outlet all together.

That's in a steel framed build,wouldn't sit anything in a loft with out structural engineers calcs....full megaflow is heavy,2 would be heavier.

 

[Dan Robinson]

I stand corrected .

Not had a chance to play with one first hand, although have some speccd waiting for the client to confirm.

 

[indus]

Theyre actually based around an accumalator not a constant pressure boost pump from a break tank.
It's all about charging to a pressure above that of the system requrements and then when your getting close to your required pressure minimum charging it back up.

View media item 19282
Thermal store an homebooster,runs 5 showers and 2 baths plus multiple sinks at 2bar with minimum of 10lpm at eac outlet all together.

That's in a steel framed build,wouldn't sit anything in a loft with out structural engineers calcs....full megaflow is heavy,2 would be heavier.

Thanks, mine is a fully converted loft with two bedrooms and large storage space. I presume there would be no issue locating them there?

And are we agreed that there is no negative impact of having the boilers on the ground floor and the cylinders in the loft? There is plenty of storage space to keep them in the loft so it would be shame to take up space on the ground floor that could be used for something else.


Thanks again

 

[SimonH2]

Don't forget that there is a lot of weight in a large cylinder full of water. Not a problem as long as it's thought about, and there's somewhere to transfer the weight to.

 

[indus]

Don't forget that there is a lot of weight in a large cylinder full of water. Not a problem as long as it's thought about, and there's somewhere to transfer the weight to.

Simon, 300 litres of water weighs 300kg. That's no different to the weight three well built guys, though I admit they won't all stand on top of each other!

However since my loft has just been converted into two bedrooms/two showers. Surely a couple of large cylinders is no problem?