Need advice on replacement boiler quote please

[HiQ]

Hello.
I am new to the forum and would welcome some views on a quote I just had from a large nationwide supplier.
Current system is in a 3 bed, 2 bath bungalow, vented HW storage, fully pumped S plan, 9 rads, 2 tanks in loft, 7 yr old Drayton (BG branded) wax filled TRV's. Boiler is Ideal icos 24he fitted by BG 7 years ago.
We have recently bought the property located on the South coast, only 2 of us in occupation 98% of time and do not heat 2 of the bedrooms and 1 bathroom. Heat requirement calculations indicate 11KW ignoring our limited use.
My 2 main reasons for changing the system are; I would like to remove the need for storage tanks in the loft and stop/minimize the currently excessive boiler short cycling.
The quote was £5,500 for a WB 30CDi combi and included the following that I would like a second opinion on:
1. The current boiler is obsolete and rubbish and will fail imminently and cannot be fixed.
2. My CH pipes being under the concrete floor will "definitely" leak with the new high pressure combi boiler.
3. I will have to disconnect (and separately replace) my Mira LP thermo mixer showers.
4. My newly installed Drayton digistat +3 will not work with the new system and I need a "HIVE" to replace it.
5. The new boiler will not short cycle as it modulates from 1W to 30W - I questioned that the technology had improved so much and he confirmed I had not misheard.
6. Replace all 8 TRV's and balance valves as the old ones will "definitely" leak.
7. Gas use will be 30% lower than now.
I will of course now obtain a quote from a small, local, company but would like to know if all the above is correct beforehand.
Many thanks in anticipation.

 

[newbuildinstaller]

1. The current boiler is obsolete and rubbish and will fail imminently and cannot be fixed.
= plenty parts for Icos as they fitted 1000,000's (though they are crap)

2. My CH pipes being under the concrete floor will "definitely" leak with the new high pressure combi boiler.
= Not necessarily but is possible, very easy to pressure test them before replacing them with a test pump and a lot cheaper to test than replace

3. I will have to disconnect (and separately replace) my Mira LP thermo mixer showers.
= yes this is true

4. My newly installed Drayton digistat +3 will not work with the new system and I need a "HIVE" to replace it.
= Defo dont need a Hive lots of cheaper alternatives

5. The new boiler will not short cycle as it modulates from 1W to 30W - I questioned that the technology had improved so much and he confirmed I had not misheard.
= Lies unless he had invented it, best modulation is about 10:1 and the WB will be more like 8/6:1 (also I would go for a bigger boiler than 30W unless you live in a shoe box )

6. Replace all 8 TRV's and balance valves as the old ones will "definitely" leak.
= again possible but not likely

7. Gas use will be 30% lower than now.
= nope unless you change the way you use the system. it will be less though but dont expect 30% savings on your gas bill

I would tell him to F@@@ off and get a good local independant

 

[HiQ]

Thank you very much newgasinstaller. Now I will be better able to understand the local installer.

 

[D_Hailsham]

1. The Icos does not have a good reputation, so it might be a good idea to phone Ideal and ask about spares availability.

2. Pipes leaking is a possibility, but you can't say it will definitely happen

3. Ask Mira about the showers

4. You don't need a "HIVE".

5. The boiler modulates down to 8kW.

6. The valves might leak. Changing them will do no harm and liquid filled TRVs are more responsive.

7. Gas use will be 30% lower than now.

Ask for that in writing on BG letterhead.

PS The reason your boiler short cycles is that it is oversized.

You need a maximum of 11kw for heating and BG is suggesting a boiler which only modulates down to 8kW. Most of the heating season it will be cycling as the heat requrement will be less than 8kW. That will be whenever the outside temperature is above approx 6C.

 

[HiQ]

Thank you very much D_Hailsham. Very interesting info about the short cycling.

 

[D_Hailsham]

Thank you very much D_Hailsham. Very interesting info about the short cycling.

I should have mentioned that the Icos only modulates down to 8.8kW, which is why it short cycles so often.

I also should have asked why you want to get rid of the tanks in the roof and, presumably, the HW cylinder.

 

[HiQ]

Thank you very much D_Hailsham. Very interesting info about the short cycling.

I should have mentioned that the Icos only modulates down to 8.8kW, which is why it short cycles so often.
Thank you that's good to know.

I also should have asked why you want to get rid of the tanks in the roof and, presumably, the HW cylinder.

I need more loft insulation but our roof is very shallow pitch and the loft tanks restrict access to over 2/3 of the roof space. The building is also step shaped (plan view) so blowing insulation in will be difficult. I also worry about leaks and repairs.

I would be happy to go with an unvented HW storage system but am told I will need to spend £ thousands increasing the size of my 22mm mains supply.

 

[Dan Robinson]

Was this a BG quote?

Haven't read so much shyte from them in ages.

The Icos was pants, but spares are readily available. Even Ideal wouldn't be so stupid as to throw away that kind of spares sales

The shower, unless a power shower may well work fine.

If you are worried about leaks in the floor, then look to an Intergas HRE24. It can remain open vented - so you can get the loft insulated then put the header tank back in. Leaving the heating system open vented whilst getting mains pressure hot water.

Plenty of good independents in your area - BG are a bunch of warnkers (present BG employed company excepted).

 

[Dan Robinson]

I would be happy to go with an unvented HW storage system but am told I will need to spend £ thousands increasing the size of my 22mm mains supply.

22mm COULD be fine. It is for my house. I have 25mm coming in dropping to 22mm and can have two showers running at the same time.


Week before last i fitted an unvented cylinder into a house with only a 15mm mains pipe. Could fill the bath in under 5 minutes:

Spraying up the sides of the bath it was - as you can see.

 

[D_Hailsham]

happy to go with an unvented HW storage system but am told I will need to spend £ thousands increasing the size of my 22mm mains supply.

You need to check your incoming cold water flow rate and pressure.

The best place to do this is the garden tap. Time how long it takes to fill a 10 litre bucket. Then convert this to litres/minute.

Now repeat but with the kitchen cold tap fully open. at the same time.

The smaller the difference, the better, as it means the pressure is good.

You need about 20 litres/min with both taps open.

PS Make sure the stop tap(s) are fully open when you check the flow.

 

[HiQ]

Thank you. I did the test and found 10 litres from the garden tap took 50 sec and then 62 sec with the sink tap full on. Unlike most houses my kitchen sink and garden tap are at the opposite end of the building from the rising main, so there is currently lots of 15mm pipe, bends and at least 2 in-line small bore isolation valves in between.

I am interested to know what is the reason for measuring the flow rate and what is the consequence if it being low with an unvented HW system.

Many thanks

 

[Dan Robinson]

Crap performance.

 

[Dan Robinson]

If you watch my video to the end you can see the sudden drop in flow rate as the accumulator runs out of charge. The Bath then falls back to the natural capacity of the system that was pants.

 

[D_Hailsham]

I am interested to know what is the reason for measuring the flow rate and what is the consequence if it being low with an unvented HW system.

Because combi boilers and unvented cylinders are both fed from the mains.

If you have 10 litres/min coming into the house you will get 10 litres/min coming out of the tap, irrespective of whether you have a combi or an UV cylinder.

Don't forget that all outlets, both hot and cold, are fed from the same incoming main, so, if someone flushes the toilet, or turns on the washing machine, while you are in the shower, you will immediately notice the effect.

10 litres/min is just about adequate for a shower with nothing else drawing water at the same time.