Boiler problems in big house - Change required?

jeff the gasman said:
Is the canoe filter clean?
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I was looking at this plastic container that protrudes outside of the bottom of the boiler. Is that the one? If so, it has a small layer of blackness at the bottom of the container. I can't see any other filters in the flow or return pipes.

Edit: just seen that the plastic container is a condensate trap
 
jeff the gasman said:
https://www.google.co.uk/search?q=v...Q7AkIfg&biw=1024&bih=729#imgrc=UI0WDJi7uRRmLM:
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Can you take a look and see it's it's the big shiny brass/copper thing to the left of the pump or the red knob to the right of the pump, or something else in here:

IMG_2963.jpg
 
Goku said:
Would a bigger pump still be beneficial with a LLH?
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You have 2+ pumps with a LLH. One pump (in your case, the one inside the boiler) pushes water around the primary side of the LLH. The second (or more) pumps, push water around the secondary (heating) side, or to individual zones. I have a single pump on my secondary side, even though I have 2 heating zones and a HW zone.

Balancing the HW cylinder will not necessarily reduce it's ability to heat. It's like balancing radiators - you balance them enough to heat up sufficiently, without stealing heat from everything else. Some prefer to have HW on priority, which means it takes all of the heat, with the idea being that it heats only for a short amount of time, and then turns off (eg. modern Unvented cylinders have a recovery time of around 20 - 25 mins).
 
Goku said:
I'm worried about fitting a gate valve because I want the hot water cylinder to get a good amount of heat when it needs it. The zone valve is working because it switches on and off with the programmer. I think the cylinder thermostat needs replacing because it's doing nothing to cut off the zone valve (no sound of a 'click' when I turn the dial down).

I'm intrigued by this low loss header concept. You're the third person to suggest hydraulic separation on this thread; so I will definitely have to look further into this. How does your set up look?
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The are various ways of doing it, here are some examples we've done recently in varying states of completion:
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Goku said:
I agree that I need a bigger pump. Reading on hydraulic separation, are you suggesting that to help our problems with the hot water circuit being given priority over the heating circuit due to its proximity? Sounds like a good idea if we have multiple zones in the house, but as we only have the two, I think I need to look into replacing the cylinder thermostat to begin with. But I will keep this suggestion in mind.

We're in London.

Counting on the emergency plumber to get the system working for now. Hoping that I can get some advice on here first before looking to an independent engineer.

We have a separate, unvented (pressurised) hot water cylinder so I don't think hot water priority is going to be suitable for our system.
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He priority would be suitable for you.

Yes a low loss header.
I’d suggest speaking to @Dan Robinson who’s posted on here, he’s experience of that size system and covers your area.
 
You could do all of the above but as a short term solution to the problem reduce the power output of the Boiler to 20kw This will stop the Boiler continually going into over run and waiting times which effectively turn the gas off for about 20 mins in every hour. If this improves the situation then the install of a low loss header will be money well spent
 
Goku said:
I'm worried about fitting a gate valve because I want the hot water cylinder to get a good amount of heat when it needs it. The zone valve is working because it switches on and off with the programmer. I think the cylinder thermostat needs replacing because it's doing nothing to cut off the zone valve (no sound of a 'click' when I turn the dial down).

I'm intrigued by this low loss header concept. You're the third person to suggest hydraulic separation on this thread; so I will definitely have to look further into this. How does your set up look?
Click to expand...

If you boiler does not deliver water at a temperature high enough to heat water in the cylinder to its thermostat setting, that thermostat will never be satisfied. Why not time the water heating to night time with a boost when heating not required.

What setting are you running the boiler at when heating water
Some boilers, do not think yours has that facility, can be set to run at different temperature, so for hot water heating boiler would run at higher temperature

Homeserve fella talking rubbish. You have a 37kw boiler. How is a 38kw boiler going to help the situation. Looking at the system stripped down, the heat exchangers for your boiler or 438 will be almost identical. System boiler has internal pump, 438 no pump so external required.

Some excellent advice already posted.
Perhaps it could be suggested you get couple of clamp thermometers and plot out temperature chart at each radiator, cylinder and at the boiler of flow and return to access where the water is going or not

Attended an 'erratic hot water delivery' call yesterday.
Used two Testo clamp thermometers to show customer boiler working fine as indicated in manual. Issue- incoming water at 4 degree C and boiler raising the temperature by 35 to deliver 40 degrees of not do hot water to the tap. Water delivery stable. Have used these Bluetooth devices to figure what is actually happening. Has been a good investment.

Look at Honeywell Evohome to heat rooms as they are occupied rather than the whole house
 
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Dan Robinson said:
The are various ways of doing it, here are some examples we've done recently in varying states of completion:
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Some beautiful looking work. Turns out the system just needed a second powerflush and now works in a way that we've never experienced since moving in. Every room heats up and the boiler is running constantly on full flame at whatever temperature we set!

Phill Peck said:
He priority would be suitable for you.

Yes a low loss header.
I’d suggest speaking to @Dan Robinson who’s posted on here, he’s experience of that size system and covers your area.
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Thanks.

snb said:
You could do all of the above but as a short term solution to the problem reduce the power output of the Boiler to 20kw This will stop the Boiler continually going into over run and waiting times which effectively turn the gas off for about 20 mins in every hour. If this improves the situation then the install of a low loss header will be money well spent
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Thanks. We got it working with a second powerflush.

DP said:
If you boiler does not deliver water at a temperature high enough to heat water in the cylinder to its thermostat setting, that thermostat will never be satisfied. Why not time the water heating to night time with a boost when heating not required.

What setting are you running the boiler at when heating water
Some boilers, do not think yours has that facility, can be set to run at different temperature, so for hot water heating boiler would run at higher temperature

Homeserve fella talking rubbish. You have a 37kw boiler. How is a 38kw boiler going to help the situation. Looking at the system stripped down, the heat exchangers for your boiler or 438 will be almost identical. System boiler has internal pump, 438 no pump so external required.

Some excellent advice already posted.
Perhaps it could be suggested you get couple of clamp thermometers and plot out temperature chart at each radiator, cylinder and at the boiler of flow and return to access where the water is going or not

Attended an 'erratic hot water delivery' call yesterday.
Used two Testo clamp thermometers to show customer boiler working fine as indicated in manual. Issue- incoming water at 4 degree C and boiler raising the temperature by 35 to deliver 40 degrees of not do hot water to the tap. Water delivery stable. Have used these Bluetooth devices to figure what is actually happening. Has been a good investment.

Look at Honeywell Evohome to heat rooms as they are occupied rather than the whole house
Click to expand...

The reason the cylinderstat was not clicking when I checked was because the water was so cold that it was below the minimum setting of the stat. After the boiler started working, I checked the stat and found that it was working as expected.
 
Thank you all for your replies. I've got the boiler working with a second powerflush. We had it run through the boiler with each radiator. In the normal flow, we had the boiler on (where it ran on full heat and full flame like a dream) and in reverse, we had the boiler off.

As per my previous reply, it's working better than we've ever experienced! The pump is serving the purpose getting a high amount of heat, almost instantly, to the furthest radiators in the house. Also, we no longer have an issue with hot water being on at the same time as heating!
 
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