Choice of boiler - options - and at last a quote!

[Simon Hawthorne]

Hi all

It seems I have finally found a reliable plumber (sorry, heating engineer as he likes to be known) - he calls when he says he will call

- and has plenty of suggestions for my 'project'.

I just wanted to bounce the options off some of you good 'informed' people - before I decide which to go for.

Current situation:

1 x 25 year old boiler 11 x 'old' rads - twin entry pipes (only one I've so far fitted TRVs to!) ?? meters of 8mm microbore pipework 1 x old hot water cyclinder 2 seperate zones (upstairs and down) - controlled by room stats 12 litres per minute out of the cold tap (possible increase to 14 if I change the supply) 2 adults living in house - 2 baths per day. No kids, got a dishwasher

- so little other need for hot water

The future:

4 zones - upstairs, loft (would like a bath and shower up here), downstairs, barn Either combi, normal hot water tank or pressurised tank About 30Kw of heat required of all 4 zones on at same time (very unlikely)

The options (as discussed with reliable plumber...!) Worcester Greenstar 30He Combi No tank of any sort (or Greenstart boiler with tank) Possible complete new system (rads/pipework etc)

So, what do you think.

He has quoted me £3k to fit Combi - and rip out old tank/header tanks/set up CH system - with the 4 zones/stats etc (either Greenstar combi or normal Greenstart boiler and hot water tank)

or

£5,500 for complete new system (new rads/pipework/boiler as above).

My gut feel is £5,500 is a fair price (i've had some silly quotes - one as muc as £14k!!) - and the guy seems straight and reliable.

Thanks in advance

Simon

[Jeff]

If you go combi then go bigger, WB do a 40 Kw, ignore heating requirement and spec on flow bearing in mind that you are only likely to get the flow stated in the summer

Regards Jeff

[Simon Hawthorne]

Thanks Jeff.

This was the original boiler we considered but I was told that due to my puny 12 litres per minute I would never get the benefit out of spending the extra money - and I only need 30Kw - maximum - and that in the unlikely event I had all 4 zones on together.

What is the benefit of going for a bigger boiler?

Thanks in advance

Si

[Jeff]

AIUI - WB 40 Kw is rated at 16 litres per min at 35 degrees temp rise so if you want water at 50 degrees you will only get 16 lpm if the mains temp is

15 degrees.... in winter its a lot colder.

Regards Jeff

[Simon Hawthorne]

Hi again Jeff

I see what you are saying - but I'll only get 12 litres per minute cold mains - so the boiler would never be used ot it's max anyway ...? Or am I missing the point.....

Si

[Jeff]

Simon Hawthorne wrote :-

Read this thread :-

help - how has your flow been measured ?

Regards Jeff

[Owain]

If your mains flow is limited then neither a combi nor pressurised tank is going to be very successful. You could use a moderately specced combi to run a shower in the loft (gets you hot water above the tanks), and have a vented cylinder h.w. system (better for flow) run on the heating circuit of the combi.

What IMM might call a win win situation except you don't need two boilers and a dedicated pipeline from the Siberian gasfields.

Owain

[Simon Hawthorne]

Mmm..... good thread Jeff, thanks.

I measured from the kitchen sink (nearest the stop c*ck) - filled a bowl for 30 seconds - then measured it into 1 litre jugs.

I need to do a little more research I think, although the heating engineer seemed to be sure that I would be wasting money going for a

40HE over a 30HE..... just because of flow rate. I spoke to SS water

- who reckoned a new mains supply would only increase my flow by about

10% (they didn't say that - they gave me PSI and bar improvemnets - I just assumed approx 10%).

Si

[Dave Plowman (News)]

Surely this depends on what size pipe is used?

[Simon Hawthorne]

I told them what I had got (length of old lead pipe). They told me what I should be getting now, and what increase I'd get if I fitted a new feed. It was approx 10% increase in bar/psi - so I've cruedly applied this to flow.

S.

[Dave Plowman (News)]

I'm not quite sure how changing the pipe can increase the pressure? The flow, yes, but they're not the same thing.

[Simon Hawthorne]

I agree - but the pipe currently travels 160 odd feet from road to house in old lead pipe (which I have had leaks in previously). I plan to have a new pipe bought in off the road (that standard blue plastic stuff) - which is only 30' away. I'm 'assuming' that the wider pipe and increase in pressure will give me a small increase in flow.

But I might be wrong.....

Even if it does improve flow, it won't be by much (the South Staffs water lady tells me!).

S.

[Christian McArdle]

Replacing the pipe will have no effect on psi. However, it could have a considerable effect on flow. If the street stays above 1 bar, a nice wide bore 30+mm MDPE pipe will provide plenty of water.

High pressure allows you to use smaller pipes. However, you can still have high flow with low pressure, if the pipes are big enough and the street pressure is stable. (It's no good if the pressure in the street drops as soon as you draw water).

Christian.

[Doctor Evil]

Have the blue pipe 32mm with a full-bore stop-c*ck. They may drop to 25mm at the street stop-c*ck, but it reduces restrictions and keeps dynamic pressure up. You may be pleasantly surprised at the performance. The dynamic pressure will be far more stable and that is the main point of household water pressure. You have only 1 bar and a decent stable flowrate and pressure that is not bad at all.

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[Christian McArdle]

I'm totally in agreement here.

Replacing 160' of ancient lead narrow bore pipe with 30' of modern 32mm MDPE should transform the flow rate.

What is the current static pressure? Does it vary during the day? To find out, get a pressure gauge and leave it connected during the day and record the readings (in bar). Only take readings when you're not using water and the loft tank is full.

If it stays over 1 bar at all times, then replacement with MDPE should be successful. This assumes that you have an urban supply. Things aren't so clear cut with a rural one.

Quite frankly, I'd replace that sort of length of lead anyway, for health reasons. A little bit of lead wouldn't worry me, but that is a lot!

Christian.

[Dave Plowman (News)]

I would very certainly expect it. Old lead pipe could be furred up or even partially crushed.

In practice, I'd expect a *dramatic* increase in flow.

[Dave Plowman (News)]

It's an interesting point. In a hard water area, the pipe will be coated.

In a soft water area - like my home town Aberdeen - a pal had his water tested as a requirement for free - or subsidised - replacement of the

100ft or so run from street to house. And the lead content was *way* below the 'statuary' limit.

Perhaps there is some intermediate type of water which does attack the lead?

Of course, it might be better to be safe than sorry. Until in a few years time they discover old MDPE pipe leeching nasties. :-)

[Doctor Evil]

.....he is at it again....

Wow!!! it all fits!! One of the worst places I have ever been to is Aberdeen. Awful grey dreary place and the people? ....well look at this one....

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[Bob Eager]

But it wouldn't matter to you. Sanatoriums are the same everywhere.

[Dave Plowman (News)]

Yup. They don't suffer fools gladly. Especially those who try and waste other's money. You must have had a dreadful time.