24kw system boiler, 15mm pipes.

markin

housebuyer143 said:

markin said:

Unless you're extending the house its odd for only a 20 year old system to be sized incorrectly?

It's a large 4 bed detached house but what I find is the boiler isn't capable of powering both the hot water and heating at the same time. If you do this the radiators at the end of the run go cold and the hot water only heats to luke warm. I wanted to upgrade the upstairs radiators to doubles also as they are ridiculously small. 

I'll get some more advice though as if a new 18kw can do the job then I'll take it, but when I explained my problem to the last engineer he instantly said we needed to upside. 

Maybe its the water tank that's to small for a 4 bed?  Heat being diverted to the water heater for 40min should not make the house cold, How long is the heating on for, And whats the heat setting/flow temp?

 

ThisIsWeird

ThisIsWeird said:

H143, we need some basic info, please:

1) Your house - type, and how many beds? Extended?
2) Distance of boiler from DHW cylinder?
3) Size of current boiler? (Make & model, please)
4) Issue you have having with current boiler?

And photos of your DHW cylinder would be helpful too, showing the pipes and valves around it. And of the underside of your current boiler showing the connected pipes.

1) Ok, it's a 4-bed detached house.
4) And the issue is that - for a yet unknown reason - the boiler cannot heat both the DHW and the furthest rads at the same time.

housebuyer143

ThisIsWeird said:

ThisIsWeird said:

H143, we need some basic info, please:

1) Your house - type, and how many beds? Extended?
2) Distance of boiler from DHW cylinder?
3) Size of current boiler? (Make & model, please)
4) Issue you have having with current boiler?

And photos of your DHW cylinder would be helpful too, showing the pipes and valves around it. And of the underside of your current boiler showing the connected pipes.

1) Ok, it's a 4-bed detached house.
4) And the issue is that - for a yet unknown reason - the boiler cannot heat both the DHW and the furthest rads at the same time.

Thank you. The boiler is a glowworm 18si, 18kw about 20 years old and my cylinder is brand new, megaflow 170ltr. 
It's located above it upstairs,so not too far away. 

House is 4 beds, dining room, 2 receptions, 2 bath. Larger then average rooms. 

As this post states, that's the main problem with it. No issues with heating water when it's on solo or how water when it's on solo but both together and it does both jobs badly 

ComicGeek

I'm not sure how changing from a 18 kW to a 24 kW boiler by itself is going to solve that. If the current boiler needs replacing, then replace it - but that is nothing to do with your current issue. Sounds like an unnecessary cost that isn't going to give you what you want.

The Megaflow 170i has a coil rating of 24.3 kW, so can take more heat than your current boiler can provide. That in itself is not a problem, as long as the tank is reheated within a reasonable period of time. Even from cold, your 18 kW boiler should reheat the cylinder in about 30-40 mins - while the radiators may get cooler during this period, that is normal and shouldn't mean that your house gets cold. If you're splitting the available heat between cylinder and radiators, then it's going to take a lot longer to reheat the cylinder, hence the lukewarm temp (assuming that someone's checked the cylinder thermostat and that's ok???).

Rather than trying to run both heating and hot water at the same time, heating the cylinder up first and then diverting fully to heating would be better.  Heat the cylinder a couple of times each day, and then the heat up period will be even shorter as you aren't reheating the whole cylinder each time.

ThisIsWeird

housebuyer143 said:

ThisIsWeird said:

ThisIsWeird said:

H143, we need some basic info, please:

1) Your house - type, and how many beds? Extended?
2) Distance of boiler from DHW cylinder?
3) Size of current boiler? (Make & model, please)
4) Issue you have having with current boiler?

And photos of your DHW cylinder would be helpful too, showing the pipes and valves around it. And of the underside of your current boiler showing the connected pipes.

1) Ok, it's a 4-bed detached house.
4) And the issue is that - for a yet unknown reason - the boiler cannot heat both the DHW and the furthest rads at the same time.

Thank you. The boiler is a glowworm 18si, 18kw about 20 years old and my cylinder is brand new, megaflow 170ltr. 
It's located above it upstairs,so not too far away. 

House is 4 beds, dining room, 2 receptions, 2 bath. Larger then average rooms. 

As this post states, that's the main problem with it. No issues with heating water when it's on solo or how water when it's on solo but both together and it does both jobs badly 

Thanks.

Any chance of the photos - of this megaflow, and of the pipes coming from the boiler?

I have to say, with the installation of a new Megaflow, I can't see 15mm water pipes being used to supply it, so I'm still confused at what this aspect of the issue is. Unless, like others have speculated, it's the gas supply pipe? Even then, I can't see how this one 24kW model can be supplied by a 15mm gas pipe when other makes cannot.

If the plumber is going by the inlet valve size, then that isn't particularly relevant either - my 30kW combi only has a 15mm gas inlet valve, but requires a 22mm pipe supply; it reduces only at the boiler.

Do you know - which pipes are being referred to with the '15mm' size?

ComicGeek

The Greenstar 4000 boiler has a separate 15mm connection for a cylinder only, with a 22mm connection for combined central heating and cylinder - has an option integral diverter valve kit to divert between cylinder and central heating. 

The OP's 1st post states 22mm gas connection. 

Megaflo cylinders have a 22mm connection for coils and water in/out.

If the 15mm pipework is the problem (wherever this is), then replace the pipework.

markin

Im just not seeing the actual problem here, Unless you only have the heating on for 2 hrs in the evening the house will be warm and the water will get re-heated, Have you just moved in and are used to a combi boiler?

housebuyer143

markin said:

Im just not seeing the actual problem here, Unless you only have the heating on for 2 hrs in the evening the house will be warm and the water will get re-heated, Have you just moved in and are used to a combi boiler?

First winter and yes used to a combi. I suppose I didn't want to heat water when it's not going to be used but maybe the way I am using it is incorrect and actually causing the issue.
I just had a radiator removed and I think the system is actually working better now.